Finish off sweet, mint? (4)
I believe the answer is:
bomb
'mint?' is the definition.
(thesaurus)
'finish off sweet' is the wordplay.
'finish off' means to remove the last letter.
'sweet' becomes 'bombe' (type of dessert or sweet).
'bombe' with its last letter taken away is 'BOMB'.
(Other definitions for bomb that I've seen before include "worn-out car" , "Explosive weapon" , "Incendiary device" , "lot of money" , "Explosive device" .)