Secret coteries disbanded (8)
I believe the answer is:
esoteric
'secret' is the definition.
(similar in meaning)
'coteries disbanded' is the wordplay.
'disbanded' indicates anagramming the letters (I've seen this in other clues).
'coteries' anagrammed gives 'ESOTERIC'.
(Other definitions for esoteric that I've seen before include "Privileged or confidential among coteries" , "Understandable by only an enlightened inner circle" , "Intelligible only to the initiated" , "Secret - restricted to initiates" , "needing privy" .)