Biased aspirant at fault (8)
I believe the answer is:
partisan
'biased' is the definition.
(similar in meaning)
'aspirant at fault' is the wordplay.
'at fault' indicates anagramming the letters.
'aspirant' is an anagram of 'PARTISAN'.
(Other definitions for partisan that I've seen before include "Happening immediately" , "Prejudiced towards a particular cause" , "champion" , "Enthusiast" , "(One) taking one side in dispute" .)