Religious groups (5)
I believe the answer is:
sects
'religious groups' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sects that I've seen before include "Schools of thought" , "Groups of people with divergent religious beliefs" , "Dissenting cliques" , "Religious factions" , "Groups of people with unconventional religious beliefs" .)