It is adopted by fifth-rate celebs and privileged (7)
I believe the answer is:
elitist
'privileged' is the definition.
'it is adopted by fifth-rate celebs' is the wordplay.
'is adopted by' indicates putting letters inside (I've seen this in other clues).
'fifth-rate celebs' becomes 'elist' (celebs several levels below A-list).
'it' going into 'elist' is 'ELITIST'.
'and' is the link.
(Other definitions for elitist that I've seen before include "Believer in the superiority of a few" , "arrogant" , "for the cream" , "Favouring a select group" , "(One who is) discriminating in favour of select few" .)