Party hit (4)
I believe the answer is:
bash
I believe this clue is a double definition.
'party' is the first definition.
(term for a party or celebration)
'hit' is the second definition.
(bash can mean to hit)
(Other definitions for bash that I've seen before include "Batter" , "Criticise -- social gathering" , "Party - punch" , "Strike violently" , "Heavy blow; party" .)