Friend supporting a Parisienne queen in a biased way (9)
I believe the answer is:
unequally
'in a biased way' is the definition.
(in an unequal or unfair way)
'friend supporting a parisienne queen' is the wordplay.
'friend' becomes 'ally' (an ally is a friend or supporter).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'a parisienne' becomes 'une' ('a' in French).
'queen' becomes 'qu' (abbreviation for queen).
'une'+'qu'='unequ'
'ally' after 'unequ' is 'UNEQUALLY'.
(Other definitions for unequally that I've seen before include "in unbalanced way" , "In an uneven manner" , "Not in identical, fair, way" .)