Simple card game (4)
(Other definitions for snap that I've seen before include "type of election" , "Photograph - without warning" , "Break under strain" , "Snarl at - photograph" , "Speak in a sharp angry tone" .)
'simple card game' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for war that I've seen before include "Combat" , "Large-scale conflict" , "Armed hostility" , "Fight" , "State of armed struggle" .)