Nothing to restrain view (7)
I believe the answer is:
opinion
'view' is the definition.
('opinion' can be a synonym of 'view')
'nothing to restrain' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to restrain' becomes 'pinion' (pinioning is a kind of restraining).
'o'+'pinion'='OPINION'
(Other definitions for opinion that I've seen before include "View, judgement" , "Belief not founded on proof or certainty" , "school of thought" , "Estimation" , "Viewpoint" .)