Religion? Charity's in it when converted (12)
I believe the answer is:
christianity
'religion?' is the definition.
(Christianity is an example)
'charity's in it when converted' is the wordplay.
'when converted' indicates anagramming the letters (I've seen this in other clues).
'charitys'+'in'+'it'='charitysinit'
'charitysinit' is an anagram of 'CHRISTIANITY'.
(Other definitions for christianity that I've seen before include "Major world religion" , "Charity's in it (anag)" .)