Favour good stock (5)
I believe the answer is:
grace
'favour' is the definition.
('grace' can be a synonym of 'favour')
'good stock' is the wordplay.
'good' becomes 'g' (abbreviation).
'stock' becomes 'race' (I've seen this before).
'g'+'race'='GRACE'
(Other definitions for grace that I've seen before include "kindness" , "See 18" , "old cricketer" , "For example, Euphrosyne" , "Comeliness" .)