Favoured (9)
'favoured' is the definition.
('prefer' can be a synonym of 'favour')
This is the entire clue.
(Other definitions for preferred that I've seen before include "choice" , "Chose before others" , "singled out" , "Was partial to" , "Liked better" .)
(Other definitions for sided that I've seen before include "Showed solidarity (with)" , "Took part with person in a dispute" , "Allied oneself (with one party)" .)
'favoured' is the definition.
This is all the clue.
(Other definitions for blessed that I've seen before include "darned" , "in heaven" , "Bedless (anag.)" , "Happy; beatified" , "Consecrated" .)