Light suit (5)
I believe the answer is:
match
I believe this clue is a double definition.
'light' is the first definition.
(I know that match is a type of light)
'suit' is the second definition.
(both can mean to go together)
(Other definitions for match that I've seen before include "Suit; fixture" , "Equal - lucifer" , "Marriage; game" , "one's struck" , "Tally; game" .)