Lighter twin (5)
I believe the answer is:
match
I believe this clue is a double definition.
'lighter' is the first definition.
(match is a kind of lighter)
'twin' is the second definition.
(I know that twin can be written as match)
(Other definitions for match that I've seen before include "Equal - lucifer" , "of little use when floodlights fail?" , "Contest; pair" , "Suit; fixture" , "Light" .)