Supporter going to match in The Crescent provides illumination to those going in (8)
I believe the answer is:
fanlight
'the crescent provides illumination to those going in' is the definition.
I can't judge whether this defines the answer.
'supporter going to match' is the wordplay.
'supporter' becomes 'fan' (fan is a kind of supporter).
'going to' says to put letters next to each other.
'match' becomes 'light' (light can mean a flame or match).
'fan'+'light'='FANLIGHT'
'in' is the link.
Can you help me to learn more?
(Other definitions for fanlight that I've seen before include "opening over the door" , "kind of window" , "elevated aperture" , "upper window?" , "Small window" .)