Quiet craftsperson is biased (8)
I believe the answer is:
partisan
'is biased' is the definition.
(similar in meaning)
'quiet craftsperson' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'craftsperson' becomes 'artisan' (I've seen this before).
'p'+'artisan'='PARTISAN'
(Other definitions for partisan that I've seen before include "pike" , "(One) taking one side in dispute" , "Enthusiast" , "Prejudiced in favour of one side" , "In Sparta (anag)" .)