Bishop managed church department (6)
I believe the answer is:
branch
'department' is the definition.
(thesaurus)
'bishop managed church' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'managed' becomes 'ran' (both can mean organised or was in charge of).
'church' becomes 'ch' (common abbreviation).
'b'+'ran'+'ch'='BRANCH'
(Other definitions for branch that I've seen before include "Division of some larger organisation" , "Secondary stem" , "Fork of a main stem" , "Arm" , "'Fork, offshoot (6)'" .)