A view of duck on the wing (7)
I believe the answer is:
opinion
'a view' is the definition.
('opinion' can be a synonym of 'view')
'duck on the wing' is the wordplay.
'duck' becomes 'o'.
'on' means one lot of letters go next to another.
'the wing' becomes 'pinion' ('pinion' can be a synonym of 'wing'**).
'o'+'pinion'='OPINION'
'of' acts as a link.
(Other definitions for opinion that I've seen before include "Conviction - point of view" , "View held without positive proof" , "Standpoint" , "Estimation" , "Belief or conviction" .)