Fairy of superiority (4)
I believe the answer is:
peri
'fairy' is the definition.
(Persian mythological being)
'of superiority' is the wordplay.
'of' says the answer is hidden in the clue.
'PERI' is hidden in the letters of 'superiority'.
(Other definitions for peri that I've seen before include "Fairy of Persian folklore" , "Malevolent Persian spirit" , "Old Persian fairy" , "Prefix denoting 'around'" , "Mythical being" .)