Bias shown by writer with song (8)
I believe the answer is:
penchant
'bias' is the definition.
(thesaurus)
'shown by writer with song' is the wordplay.
'shown by' is a charade indicator (letters next to each other).
'writer with' becomes 'pen' (I've seen this in other clues).
'song' becomes 'chant' (I've seen this before).
'pen' put next to 'chant' is 'PENCHANT'.
(Other definitions for penchant that I've seen before include "Inclination, bent" , "Inclination; taste" , "'Predilection, a strong liking (8)'" , "Leaning towards or liking for" , "Fondness (for) - bias (towards)" .)