Genuine Jedi fan obsesses somewhat in retirement (4,4)
I believe the answer is:
bona fide
'genuine' is the definition.
(similar in meaning)
'jedi fan obsesses somewhat in retirement' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'in retirement' says the letters should be written backwards (retire can mean to go back or backwards).
'edifanob' is hidden in the letters of 'jedi fan obsesses'.
'edifanob' backwards is 'BONA FIDE'.
(Other definitions for bona fide that I've seen before include "Genuine, without fraud - in Latin" , "Genuine or in good faith" , "it's on the level" , "honest - with 12a" , "(Proof of being) genuine" .)