Sanction a very quiet wander (7)
I believe the answer is:
approve
'sanction' is the definition.
('approve' can be a synonym of 'sanction')
'a very quiet wander' is the wordplay.
'very quiet' becomes 'pp'.
'wander' becomes 'rove' ('rove' can be a synonym of 'wander').
'a'+'pp'+'rove'='APPROVE'
(Other definitions for approve that I've seen before include "Give sanctions to" , "Consider right" , "Give the nod to, sanction" , "Give thumbs-up to" , "permit" .)