Most aristocratic not really favoured (7)
I believe the answer is:
noblest
'most aristocratic' is the definition.
('noble' can be similar in meaning to 'aristocratic')
'not really favoured' is the wordplay.
'not' becomes 'no' (I've seen this in other clues).
'really favoured' becomes 'blest' (archaic version of blessed).
'no'+'blest'='NOBLEST'
(Other definitions for noblest that I've seen before include "Most magnificent" , "Highest-ranking" , "Most refined" , "Most distinguished" , "most generous" .)