Permit one art house composition (9)
I believe the answer is:
authorise
'permit' is the definition.
(I know that authorise is a more specific form of the action permit)
'one art house composition' is the wordplay.
'one' becomes 'i' (Roman numeral).
'composition' is an anagram indicator (letters arranged or composed in a different order).
'i'+'art'+'house'='iarthouse'
'iarthouse' is an anagram of 'AUTHORISE'.
(Other definitions for authorise that I've seen before include "commission" , "warrant" , "OK" , "Give official permission to" , "Sanction, empower" .)