A game of quick decision (4)
I believe the answer is:
snap
'a game' is the definition.
(card game)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for snap that I've seen before include "Take a photo" , "Simple card game - gotcha!" , "Break sharply - a simple card game" , "Unpremeditated - bite" , "unexpected? > Same here!" .)