A fairy in the upper income bracket (4)
I believe the answer is:
peri
'a fairy' is the definition.
(Persian mythological being)
'in the upper income bracket' is the wordplay.
'in' indicates the answer is hidden within the clue.
'PERI' is hidden in the letters of 'upper income bracket'.
(Other definitions for peri that I've seen before include "Fairy queen" , "Old Persian fairy" , "Type of disembodied spirit or graceful young girl" , "Spirit of folklore" , "Beautiful fairy" .)