Possibly one employed by great church (8)
I believe the answer is:
minister
'possibly one employed by great church' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
This is all the clue.
Can you help me to learn more?
(Other definitions for minister that I've seen before include "Member of parliament" , "Member of government or clergy" , "parliamentarian" , "Political or religious official" , "Holder of office in government or church" .)