Division into opposing factions (6)
I believe the answer is:
schism
'division into opposing factions' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for schism that I've seen before include "(Ecclesiastical) division" , "Split (usually in church)" , "Dividing of group into opposing factions" , "Friction or division in church organisation" , "Deep division" .)