- Do not mix spaces and tabs for indentation (line 11 and 12)

 - Wrap the description to stay below 80 characters per line:

%description
Clipmenu is a simple clipboard manager using dmenu (or rofi with
CM_LAUNCHER=rofi) and xsel.


 - /usr/lib/systemd/user -> %{_userunitdir}

 - Use systemd scriptlets, see https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/#_user_units

%post
systemctl daemon-reload

->

BuildRequires: systemd-rpm-macros

[…]

%post
%systemd_user_post clipmenud.service

%preun
%systemd_user_preun clipmenud.service


 - The changelog entry must contain your name, email and version-release number:

%changelog
* Thu May 06 2021 kvlad <v.a.kim1988> - 6.2.0-1
- First clipmenu package

 - Use a more explicit name for your archive:

Source0:        https://github.com/cdown/%{name}/archive/%{version}/%{name}-%{version}.tar.gz


 - Use setup - q to make the setup quiet:

%prep
%setup -q


Package Review
==============

Legend:
[x] = Pass, [!] = Fail, [-] = Not applicable, [?] = Not evaluated
[ ] = Manual review needed


Issues:
=======
- systemd_user_post is invoked in %post and systemd_user_preun in %preun
  for Systemd user units service files.
  Note: Systemd user unit service file(s) in clipmenu
  See: https://docs.fedoraproject.org/en-US/packaging-
  guidelines/Scriptlets/#_user_units


===== MUST items =====

Generic:
[x]: Package is licensed with an open-source compatible license and meets
     other legal requirements as defined in the legal section of Packaging
     Guidelines.
[x]: License field in the package spec file matches the actual license.
     Note: Checking patched sources after %prep for licenses. Licenses
     found: "Unknown or generated", "*No copyright* the Unlicense". 11
     files have unknown license. Detailed output of licensecheck in
     /home/bob/packaging/review/clipmenu/review-clipmenu/licensecheck.txt
[x]: %build honors applicable compiler flags or justifies otherwise.
[x]: Package contains no bundled libraries without FPC exception.
[x]: Changelog in prescribed format.
[x]: Sources contain only permissible code or content.
[-]: Package contains desktop file if it is a GUI application.
[-]: Development files must be in a -devel package
[x]: Package uses nothing in %doc for runtime.
[x]: Package consistently uses macros (instead of hard-coded directory
     names).
[x]: Package is named according to the Package Naming Guidelines.
[x]: Package does not generate any conflict.
[x]: Package obeys FHS, except libexecdir and /usr/target.
[-]: If the package is a rename of another package, proper Obsoletes and
     Provides are present.
[x]: Requires correct, justified where necessary.
[x]: Spec file is legible and written in American English.
[x]: Package contains systemd file(s) if in need.
[-]: Useful -debuginfo package or justification otherwise.
[x]: Package is not known to require an ExcludeArch tag.
[x]: Package complies to the Packaging Guidelines
[x]: Package successfully compiles and builds into binary rpms on at least
     one supported primary architecture.
[x]: Package installs properly.
[x]: Rpmlint is run on all rpms the build produces.
     Note: There are rpmlint messages (see attachment).
[x]: If (and only if) the source package includes the text of the
     license(s) in its own file, then that file, containing the text of the
     license(s) for the package is included in %license.
[x]: Package requires other packages for directories it uses.
[x]: Package does not own files or directories owned by other packages.
[x]: Package uses either %{buildroot} or $RPM_BUILD_ROOT
[x]: Package does not run rm -rf %{buildroot} (or $RPM_BUILD_ROOT) at the
     beginning of %install.
[x]: Macros in Summary, %description expandable at SRPM build time.
[x]: Dist tag is present.
[x]: Package does not contain duplicates in %files.
[x]: Permissions on files are set properly.
[x]: Package use %makeinstall only when make install DESTDIR=... doesn't
     work.
[x]: Package is named using only allowed ASCII characters.
[x]: Package does not use a name that already exists.
[x]: Package is not relocatable.
[x]: Sources used to build the package match the upstream source, as
     provided in the spec URL.
[x]: Spec file name must match the spec package %{name}, in the format
     %{name}.spec.
[x]: File names are valid UTF-8.
[x]: Large documentation must go in a -doc subpackage. Large could be size
     (~1MB) or number of files.
     Note: Documentation size is 0 bytes in 0 files.
[x]: Packages must not store files under /srv, /opt or /usr/local

===== SHOULD items =====

Generic:
[x]: If the source package does not include license text(s) as a separate
     file from upstream, the packager SHOULD query upstream to include it.
[x]: Final provides and requires are sane (see attachments).
[?]: Package functions as described.
[x]: Latest version is packaged.
[x]: Package does not include license text files separate from upstream.
[-]: Sources are verified with gpgverify first in %prep if upstream
     publishes signatures.
     Note: gpgverify is not used.
[-]: Description and summary sections in the package spec file contains
     translations for supported Non-English languages, if available.
[x]: Package should compile and build into binary rpms on all supported
     architectures.
[-]: %check is present and all tests pass.
[x]: Packages should try to preserve timestamps of original installed
     files.
[x]: Reviewer should test that the package builds in mock.
[x]: Buildroot is not present
[x]: Package has no %clean section with rm -rf %{buildroot} (or
     $RPM_BUILD_ROOT)
[x]: No file requires outside of /etc, /bin, /sbin, /usr/bin, /usr/sbin.
[x]: Packager, Vendor, PreReq, Copyright tags should not be in spec file
[x]: Sources can be downloaded from URI in Source: tag
[x]: SourceX is a working URL.
[x]: Spec use %global instead of %define unless justified.

===== EXTRA items =====

Generic:
[x]: Rpmlint is run on all installed packages.
     Note: There are rpmlint messages (see attachment).
[x]: Large data in /usr/share should live in a noarch subpackage if package
     is arched.
[x]: Spec file according to URL is the same as in SRPM.


Rpmlint
-------
Checking: clipmenu-6.2.0-1.fc35.x86_64.rpm
          clipmenu-6.2.0-1.fc35.src.rpm
clipmenu.x86_64: W: spelling-error %description -l en_US rofi -> profit
clipmenu.x86_64: E: description-line-too-long C Clipmenu is a simple clipboard manager using dmenu (or rofi with CM_LAUNCHER=rofi) and xsel.
clipmenu.x86_64: W: incoherent-version-in-changelog vlad ['6.2.0-1.fc35', '6.2.0-1']
clipmenu.x86_64: E: no-binary
clipmenu.x86_64: W: no-documentation
clipmenu.x86_64: W: no-manual-page-for-binary clipctl
clipmenu.x86_64: W: no-manual-page-for-binary clipdel
clipmenu.x86_64: W: no-manual-page-for-binary clipfsck
clipmenu.x86_64: W: no-manual-page-for-binary clipmenu
clipmenu.x86_64: W: no-manual-page-for-binary clipmenud
clipmenu.src: W: spelling-error Summary(en_US) dmenu -> menu, d menu, madmen
clipmenu.src: W: spelling-error %description -l en_US dmenu -> menu, d menu, madmen
clipmenu.src: W: spelling-error %description -l en_US rofi -> profit
clipmenu.src: W: spelling-error %description -l en_US xsel -> sell
clipmenu.src: E: description-line-too-long C Clipmenu is a simple clipboard manager using dmenu (or rofi with CM_LAUNCHER=rofi) and xsel.
clipmenu.src:23: W: setup-not-quiet
clipmenu.src: W: no-%build-section
clipmenu.src:11: W: mixed-use-of-spaces-and-tabs (spaces: line 1, tab: line 11)
2 packages and 0 specfiles checked; 3 errors, 15 warnings.

(In reply to Robert-André Mauchin 🐧 from comment #1)
>  - Do not mix spaces and tabs for indentation (line 11 and 12)
> 
>  - Wrap the description to stay below 80 characters per line:
> 
> %description
> Clipmenu is a simple clipboard manager using dmenu (or rofi with
> CM_LAUNCHER=rofi) and xsel.
> 
> 
>  - /usr/lib/systemd/user -> %{_userunitdir}
> 
>  - Use systemd scriptlets, see
> https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/
> #_user_units
> 
> %post
> systemctl daemon-reload
> 
> ->
> 
> BuildRequires: systemd-rpm-macros
> 
> […]
> 
> %post
> %systemd_user_post clipmenud.service
> 
> %preun
> %systemd_user_preun clipmenud.service
> 
> 
>  - The changelog entry must contain your name, email and version-release
> number:
> 
> %changelog
> * Thu May 06 2021 kvlad <v.a.kim1988> - 6.2.0-1
> - First clipmenu package
> 
>  - Use a more explicit name for your archive:
> 
> Source0:       
> https://github.com/cdown/%{name}/archive/%{version}/%{name}-%{version}.tar.gz
> 
> 
>  - Use setup - q to make the setup quiet:
> 
> %prep
> %setup -q
> 
> 
> Package Review
> ==============
> 
> Legend:
> [x] = Pass, [!] = Fail, [-] = Not applicable, [?] = Not evaluated
> [ ] = Manual review needed
> 
> 
> Issues:
> =======
> - systemd_user_post is invoked in %post and systemd_user_preun in %preun
>   for Systemd user units service files.
>   Note: Systemd user unit service file(s) in clipmenu
>   See: https://docs.fedoraproject.org/en-US/packaging-
>   guidelines/Scriptlets/#_user_units
> 
> 
> ===== MUST items =====
> 
> Generic:
> [x]: Package is licensed with an open-source compatible license and meets
>      other legal requirements as defined in the legal section of Packaging
>      Guidelines.
> [x]: License field in the package spec file matches the actual license.
>      Note: Checking patched sources after %prep for licenses. Licenses
>      found: "Unknown or generated", "*No copyright* the Unlicense". 11
>      files have unknown license. Detailed output of licensecheck in
>      /home/bob/packaging/review/clipmenu/review-clipmenu/licensecheck.txt
> [x]: %build honors applicable compiler flags or justifies otherwise.
> [x]: Package contains no bundled libraries without FPC exception.
> [x]: Changelog in prescribed format.
> [x]: Sources contain only permissible code or content.
> [-]: Package contains desktop file if it is a GUI application.
> [-]: Development files must be in a -devel package
> [x]: Package uses nothing in %doc for runtime.
> [x]: Package consistently uses macros (instead of hard-coded directory
>      names).
> [x]: Package is named according to the Package Naming Guidelines.
> [x]: Package does not generate any conflict.
> [x]: Package obeys FHS, except libexecdir and /usr/target.
> [-]: If the package is a rename of another package, proper Obsoletes and
>      Provides are present.
> [x]: Requires correct, justified where necessary.
> [x]: Spec file is legible and written in American English.
> [x]: Package contains systemd file(s) if in need.
> [-]: Useful -debuginfo package or justification otherwise.
> [x]: Package is not known to require an ExcludeArch tag.
> [x]: Package complies to the Packaging Guidelines
> [x]: Package successfully compiles and builds into binary rpms on at least
>      one supported primary architecture.
> [x]: Package installs properly.
> [x]: Rpmlint is run on all rpms the build produces.
>      Note: There are rpmlint messages (see attachment).
> [x]: If (and only if) the source package includes the text of the
>      license(s) in its own file, then that file, containing the text of the
>      license(s) for the package is included in %license.
> [x]: Package requires other packages for directories it uses.
> [x]: Package does not own files or directories owned by other packages.
> [x]: Package uses either %{buildroot} or $RPM_BUILD_ROOT
> [x]: Package does not run rm -rf %{buildroot} (or $RPM_BUILD_ROOT) at the
>      beginning of %install.
> [x]: Macros in Summary, %description expandable at SRPM build time.
> [x]: Dist tag is present.
> [x]: Package does not contain duplicates in %files.
> [x]: Permissions on files are set properly.
> [x]: Package use %makeinstall only when make install DESTDIR=... doesn't
>      work.
> [x]: Package is named using only allowed ASCII characters.
> [x]: Package does not use a name that already exists.
> [x]: Package is not relocatable.
> [x]: Sources used to build the package match the upstream source, as
>      provided in the spec URL.
> [x]: Spec file name must match the spec package %{name}, in the format
>      %{name}.spec.
> [x]: File names are valid UTF-8.
> [x]: Large documentation must go in a -doc subpackage. Large could be size
>      (~1MB) or number of files.
>      Note: Documentation size is 0 bytes in 0 files.
> [x]: Packages must not store files under /srv, /opt or /usr/local
> 
> ===== SHOULD items =====
> 
> Generic:
> [x]: If the source package does not include license text(s) as a separate
>      file from upstream, the packager SHOULD query upstream to include it.
> [x]: Final provides and requires are sane (see attachments).
> [?]: Package functions as described.
> [x]: Latest version is packaged.
> [x]: Package does not include license text files separate from upstream.
> [-]: Sources are verified with gpgverify first in %prep if upstream
>      publishes signatures.
>      Note: gpgverify is not used.
> [-]: Description and summary sections in the package spec file contains
>      translations for supported Non-English languages, if available.
> [x]: Package should compile and build into binary rpms on all supported
>      architectures.
> [-]: %check is present and all tests pass.
> [x]: Packages should try to preserve timestamps of original installed
>      files.
> [x]: Reviewer should test that the package builds in mock.
> [x]: Buildroot is not present
> [x]: Package has no %clean section with rm -rf %{buildroot} (or
>      $RPM_BUILD_ROOT)
> [x]: No file requires outside of /etc, /bin, /sbin, /usr/bin, /usr/sbin.
> [x]: Packager, Vendor, PreReq, Copyright tags should not be in spec file
> [x]: Sources can be downloaded from URI in Source: tag
> [x]: SourceX is a working URL.
> [x]: Spec use %global instead of %define unless justified.
> 
> ===== EXTRA items =====
> 
> Generic:
> [x]: Rpmlint is run on all installed packages.
>      Note: There are rpmlint messages (see attachment).
> [x]: Large data in /usr/share should live in a noarch subpackage if package
>      is arched.
> [x]: Spec file according to URL is the same as in SRPM.
> 
> 
> Rpmlint
> -------
> Checking: clipmenu-6.2.0-1.fc35.x86_64.rpm
>           clipmenu-6.2.0-1.fc35.src.rpm
> clipmenu.x86_64: W: spelling-error %description -l en_US rofi -> profit
> clipmenu.x86_64: E: description-line-too-long C Clipmenu is a simple
> clipboard manager using dmenu (or rofi with CM_LAUNCHER=rofi) and xsel.
> clipmenu.x86_64: W: incoherent-version-in-changelog vlad ['6.2.0-1.fc35',
> '6.2.0-1']
> clipmenu.x86_64: E: no-binary
> clipmenu.x86_64: W: no-documentation
> clipmenu.x86_64: W: no-manual-page-for-binary clipctl
> clipmenu.x86_64: W: no-manual-page-for-binary clipdel
> clipmenu.x86_64: W: no-manual-page-for-binary clipfsck
> clipmenu.x86_64: W: no-manual-page-for-binary clipmenu
> clipmenu.x86_64: W: no-manual-page-for-binary clipmenud
> clipmenu.src: W: spelling-error Summary(en_US) dmenu -> menu, d menu, madmen
> clipmenu.src: W: spelling-error %description -l en_US dmenu -> menu, d menu,
> madmen
> clipmenu.src: W: spelling-error %description -l en_US rofi -> profit
> clipmenu.src: W: spelling-error %description -l en_US xsel -> sell
> clipmenu.src: E: description-line-too-long C Clipmenu is a simple clipboard
> manager using dmenu (or rofi with CM_LAUNCHER=rofi) and xsel.
> clipmenu.src:23: W: setup-not-quiet
> clipmenu.src: W: no-%build-section
> clipmenu.src:11: W: mixed-use-of-spaces-and-tabs (spaces: line 1, tab: line
> 11)
> 2 packages and 0 specfiles checked; 3 errors, 15 warnings.

Hi! Spec file is updated.

rpmlint SPECS/clipmenu.spec 
SPECS/clipmenu.spec: W: no-%build-section
0 packages and 1 specfiles checked; 0 errors, 1 warnings.

LGTM, package approved.

You still need to find a sponsor: https://fedoraproject.org/wiki/How_to_get_sponsored_into_the_packager_group