Separation of Greek characters participating in kinky sex (6)
I believe the answer is:
schism
'separation' is the definition.
(I know that schism is a type of breach)
'greek characters participating in kinky sex' is the wordplay.
'greek characters' becomes 'chis' (I've seen this in another clue).
'participating in' is an insertion indicator.
'kinky sex' becomes 'SM' (S and M, sadism and masochism).
'chis' put within 'sm' is 'SCHISM'.
'of' is the link.
(Other definitions for schism that I've seen before include "Formal split in a church" , "Division of a group into opposing factions" , "Friction or division in church organisation" , "Split in church unity" , "Breach within a Chruch" .)