Reality One on this clique (7)
I believe the answer is:
faction
'this clique' is the definition.
(faction is a kind of clique)
'reality one on' is the wordplay.
'reality' becomes 'fact' (fact is a kind of reality).
'one' becomes 'i' (Roman numeral).
'fact'+'i'+'on'='FACTION'
(Other definitions for faction that I've seen before include "Cabal" , "Act on if for a small group within a larger one" , "Wing" , "Small trouble-making group within a group" , "Dissenting group - drama documentary" .)