Sharp witticism by chap (7)
I believe the answer is:
pungent
'sharp' is the definition.
(thesaurus)
'witticism by chap' is the wordplay.
'witticism' becomes 'pun' (pun is a kind of witticism).
'by' says to put letters next to each other.
'chap' becomes 'gent' (I've seen this in other clues**).
'pun'+'gent'='PUNGENT'
(Other definitions for pungent that I've seen before include "Offensive" , "Strong-smelling" , "spicy" , "Penetrating" , "Incisive" .)