Faux pas from the boss, finishing early (5)
I believe the answer is:
gaffe
'faux pas' is the definition.
(thesaurus)
'the boss finishing early' is the wordplay.
'the boss' becomes 'gaffer' ('gaffer' can be a synonym of 'boss').
'finishing early' means to remove the last letter.
'gaffer' with its last letter removed is 'GAFFE'.
'from' is the link.
(Other definitions for gaffe that I've seen before include "Blundering remark" , "A foolish error" , "Clanger" , "Remark one wishes unmade" , "Tactless remark" .)