Convert put up in church (6)
I believe the answer is:
change
'convert' is the definition.
('change' can be a synonym of 'convert')
'put up in church' is the wordplay.
'put up' becomes 'hang' (I've seen this in other clues).
'in' indicates putting letters inside.
'church' becomes 'ce' (abbreviation for Church of England).
'hang' going into 'ce' is 'CHANGE'.
(Other definitions for change that I've seen before include "Word for small coins in pocket" , "Coppers, perhaps" , "Best not to do it in 12" , "Little pieces" , "Coins of low value" .)