Sudden break for card game (4)
I believe the answer is:
snap
I believe this clue is a double definition.
'sudden break' is the first definition.
(I've seen this before)
'for card game' is the second definition.
(simple card game)
(Other definitions for snap that I've seen before include "Break like informal photo" , "Take a photo" , "Break; liveliness" , "Break with a crack" , "Break suddenly and abruptly" .)