In France, who quietly delivers a bon mot? (4)
I believe the answer is:
quip
'a bon mot?' is the definition.
(thesaurus)
'in france who quietly' is the wordplay.
'in france who' becomes 'qui' (French for 'who').
'quietly' becomes 'p' (p for piano and quiet).
'qui'+'p'='QUIP'
'delivers' is the link.
(Other definitions for quip that I've seen before include "Quick witty remark" , "Funny remark" , "Witticism" , "Crack" , "clever observations" .)