bibtex-clean-entry is an interactive compiled Lisp function in `bibtex.el'.

(bibtex-clean-entry &optional NEW-KEY CALLED-BY-REFORMAT)

Finish editing the current BibTeX entry and clean it up.
Check that no required fields are empty and format entry dependent
on the value of `bibtex-entry-format'.
If the reference key of the entry is empty or a prefix argument is given,
calculate a new reference key. (Note: this works only if fields in entry
begin on separate lines prior to calling `bibtex-clean-entry' or if
'realign is contained in `bibtex-entry-format'.)
Don't call `bibtex-clean-entry' on @Preamble entries.
At end of the cleaning process, the functions in
`bibtex-clean-entry-hook' are called with region narrowed to entry.