Bridge coup (4)
I believe the answer is:
slam
'bridge coup' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for slam that I've seen before include "If it's grand, it wins all 13 tricks in bridge game" , "Criticise - bang - very good result at bridge" , "Winning all (or all but one) of the tricks in bridge" , "Shut hard" , "Hit hard" .)