Religious group or division (6)
I believe the answer is:
sector
'division' is the definition.
(thesaurus)
'religious group or' is the wordplay.
'religious group' becomes 'sect' (I've seen this before**).
'sect'+'or'='SECTOR'
(Other definitions for sector that I've seen before include "Specific group as part of the economy" , "A branch of enterprise" , "Quarter - subdivision" , "District" , "Corset for part of battle area" .)