Sanction demolition (9)
I believe the answer is:
clearance
I believe this is a double definition.
'sanction' is the first definition.
(clearance is a kind of sanction)
'demolition' is the second definition.
(I've seen this before)
(Other definitions for clearance that I've seen before include "Permission to proceed" , "Official authorisation" , "spare room" , "Intervening space" , "Vacation" .)