Nothing you said that's wrong or not genuine (4)
I believe the answer is:
faux
'not genuine' is the definition.
(I've seen this in another clue)
'nothing you said that's wrong' is the wordplay.
'nothing' becomes 'FA' (slang term - sweet Fanny Adams).
'you said' becomes 'U' (homophone of 'you').
'that's wrong' becomes 'x' (X is used to mark something as incorrect).
'fa'+'u'+'x'='FAUX'
'or' is the link.
(Other definitions for faux that I've seen before include "Bogus" , "Artificial" , "Fake" .)