Party is a hit (4)
I believe the answer is:
bash
This clue is a double definition.
'party' is the first definition.
(term for a party or celebration)
'is a hit' is the second definition.
(I've seen this before)
(Other definitions for bash that I've seen before include "Party - clobber" , "Go" , "Criticise -- social gathering" , "Smite; a party" , "Party; attempt (slang)" .)