Light rent reduced with support of church (5)
I believe the answer is:
torch
'light' is the definition.
(torch is a kind of light)
'rent reduced with support of church' is the wordplay.
'rent' becomes 'torn' ('torn' can be a synonym of 'rent').
'reduced' means to remove the last letter.
'with' means one lot of letters go next to another.
'support of church' becomes 'ch' (I've seen this in other clues).
'torn' with its last letter removed is 'tor'.
'tor'+'ch'='TORCH'
(Other definitions for torch that I've seen before include "Portable lamp; set alight" , "source of illumination" , "Set fire to (something)" , "Portable light; burn" , "Burn maliciously" .)