Father's dark brown — or fair? (8)
I believe the answer is:
passable
'fair?' is the definition.
(synonyms)
'father's dark brown' is the wordplay.
'father's' becomes 'pa's' (pa can mean dad or father).
'dark brown' becomes 'sable' (dark brown fur).
'pas'+'sable'='PASSABLE'
'or' is the link.
(Other definitions for passable that I've seen before include "Merely satisfactory" , "Fair" , "examinations should be!" , "Fairly good but not outstanding" , "All right" .)