Fight during his party (4)
I believe the answer is:
spar
'fight' is the definition.
(I know that spar is a more specific form of the action fight)
'during his party' is the wordplay.
'during' says the answer is hidden in the clue.
'SPAR' is hidden within 'his party'.
(Other definitions for spar that I've seen before include "Train at boxing; mineral" , "A mineral; nautical pole" , "Box; various minerals" , "Pole used to support sails or rigging" , "have an argument without marked hostility" .)