`\fulllcite` vs bibliography listing with Biblatex when fields are removed

Question

The Biblatex documentation says "the \fullcite command prints a verbose citation similar to the full bibliography entry". There are some differences though, and some questions/answers here about that, like this and this.

Here is another way they differ:

\documentclass{article}
\usepackage{biblatex}
\addbibresource{biblatex-examples.bib}
% Don't want to see "language" field.
\AtEveryBibitem{\clearlist{language}}
\begin{document}
\fullcite{cicero}
\printbibliography
\end{document}

This uses a suggested method of removing the language field. It is removed from the bibliography, but not from the \fullcite output. How can I get rid of it there as well?

The output:

Answer 1

\AtEveryBibitem indeed does not affect \fullcite because it is a citation command, and not a bibitem. But you can use \AtEveryCitekey for this:

\documentclass{article}
\usepackage{biblatex}
\addbibresource{biblatex-examples.bib}
% Don't want to see "language" field.
\AtEveryBibitem{\clearlist{language}}
\AtEveryCitekey{\clearlist{language}}
\begin{document}
\fullcite{cicero}
\printbibliography
\end{document}

But, given what you want to do, perhaps using a source map changing the actual data biber takes into account would be a good idea:

\documentclass{article}
\usepackage{biblatex}
\addbibresource{biblatex-examples.bib}
% Don't want to see "language" field.
\DeclareSourcemap{
  \maps[datatype=bibtex]{
    \map{
      \step[fieldset=language, null]
    }
  }
}
\begin{document}
\fullcite{cicero}
\printbibliography
\end{document}

In either case, the output is: