Sanction unit in renovated art house (9)
I believe the answer is:
authorise
'sanction' is the definition.
(I know that sanction is a more specific form of the action authorise)
'unit in renovated art house' is the wordplay.
'unit' becomes 'I' (resembles 1, a unit).
'in' indicates putting letters inside.
'renovated' indicates an anagram.
'art'+'house'='arthouse'
'arthouse' is an anagram of 'authorse'.
'i' going within 'authorse' is 'AUTHORISE'.
(Other definitions for authorise that I've seen before include "OK" , "I share out (anag.)" , "Sanction, empower" , "commission" , "Give power to or sanction" .)