Money making writer join church (5)
I believe the answer is:
pence
'money' is the definition.
(I've seen this before)
'writer join church' is the wordplay.
'writer' becomes 'pen' (something which writes).
'join' is a charade indicator (letters next to each other).
'church' becomes 'CE' (Church of England).
'pen'+'ce'='PENCE'
'making' is the link.
(Other definitions for pence that I've seen before include "Low-value coinage" , "Small quantity of money" , "Lowest denomination of British currency" , "''... fumble in a greasy till/and add the halfpence to the ...'' (Yeats)" , "Little coins" .)