The old man's fur is okay (8)
I believe the answer is:
passable
'is okay' is the definition.
(thesaurus)
'the old man's fur' is the wordplay.
'the old man's' becomes 'pas' ('pa' can be a synonym of 'old man').
'fur' becomes 'sable' (sable is a kind of fur).
'pas'+'sable'='PASSABLE'
(Other definitions for passable that I've seen before include "OK" , "Barely adequate" , "All right" , "okay?" , "Fair" .)