Fair rental, I conceded, is different, not identical (9)
I believe the answer is:
fraternal
'not identical' is the definition.
('fraternal' is the opposite to 'identical')
'fair rental i conceded is different' is the wordplay.
'conceded' suggests deleting specific letters (concede can mean to give up).
'is different' is an anagram indicator (letters placed in a different order).
'fair'+'rental'='fairrental'
'fairrental' with 'i' removed is 'farrental'.
'farrental' is an anagram of 'FRATERNAL'.
(Other definitions for fraternal that I've seen before include "Affectionate like brothers" , "from an association" , "Brotherly" .)