Striker in game (5)
I believe the answer is:
match
I believe this clue is a double definition.
'striker' is the first definition.
(a match can be struck)
'game' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for match that I've seen before include "Partnership" , "Equivalent" , "tie" , "Correspondence" , "Contest; pair" .)