A blow for the party! (4)
I believe the answer is:
bash
I believe this clue is a double definition.
'a blow' is the first definition.
(I know that bash is a type of blow)
'party' is the second definition.
(term for a party or celebration)
'for the' is the link.
(Other definitions for bash that I've seen before include "crash > party" , "Go" , "Party; beat" , "Heavy blow; party" , "Criticise -- social gathering" .)