Fob Diane off for real (4,4)
I believe the answer is:
bona fide
'real?' is the definition.
(I've seen this before)
'fob diane off' is the wordplay.
'off' indicates an anagram.
'fob'+'diane'='fobdiane'
'fobdiane' is an anagram of 'BONA FIDE'.
'for' acts as a link.
(Other definitions for bona fide that I've seen before include "Real, genuine (Latin)" , "Authentic" , "(Proof of being) genuine" , "Genuine, without fraud - in Latin" , "Genuine or in good faith" .)