Change pound before church (5)
I believe the answer is:
pence
'change' is the definition.
(I have seen 'Small change ' mean 'pence' so perhaps 'change' could also mean 'pence')
'pound before church' is the wordplay.
'pound' becomes 'pen' (I've seen this before).
'before' means one lot of letters go next to another.
'church' becomes 'ce' (abbreviation for Church of England).
'pen'+'ce'='PENCE'
(Other definitions for pence that I've seen before include "They were hundredths of a pound" , "British coins" , "Old coins" , "Small coins" , "Copper coins" .)