Striker fit (5)
I believe the answer is:
match
I believe this is a double definition.
'striker' is the first definition.
(a match can be struck)
'fit' is the second definition.
(as in matching objects fitting together)
(Other definitions for match that I've seen before include "Contest; pair" , "of little use when floodlights fail?" , "Contest; correspond" , "An exact duplicate or a contest between two" , "Correspondence" .)