Acted as administrator of church farm (5)
I believe the answer is:
ranch
'farm' is the definition.
(ranch is a kind of farm)
'acted as administrator of church' is the wordplay.
'acted as administrator of' becomes 'ran' (to administrate something is to run or organise it).
'church' becomes 'ch' (common abbreviation).
'ran'+'ch'='RANCH'
(Other definitions for ranch that I've seen before include "tear for a poet" , "stock holding?" , "Agricultural business" , "Where to keep stock" , "Large farm rearing particular livestock" .)