Notes United fans as biased (11)
I believe the answer is:
tendentious
'biased' is the definition.
(thesaurus)
'notes united fans' is the wordplay.
'fans' indicates anagramming the letters (I've seen 'fanned' mean this (I've seen this in other clues)).
'notes'+'united'='notesunited'
'notesunited' with letters rearranged gives 'TENDENTIOUS'.
'as' is the link.
(Other definitions for tendentious that I've seen before include "Having deliberate bias towards a controversial view" , "partisan" , "Purposely biased (towards controversy)" , "Purposeful" , "Designed to promote a particular point of view" .)