Money a deaconess finally invested in church (4)
I believe the answer is:
cash
'money' is the definition.
(thesaurus)
'a deaconess finally invested in church' is the wordplay.
'finally' indicates one should take the final letters.
'invested in' is an insertion indicator.
'church' becomes 'ch' (common abbreviation**).
The final letter of 'deaconess' is 's'.
'a'+'s'='as'
'as' inserted into 'ch' is 'CASH'.
(Other definitions for cash that I've seen before include "Singer Johnny, d. 2003" , "Till" , "Funds" , "Ready money" , "Wimbledon champion" .)