Not at home to permit market (6)
I believe the answer is:
outlet
'market' is the definition.
(I've seen this before)
'not at home to permit' is the wordplay.
'not at home' becomes 'out' (out can mean away from home).
'to permit' becomes 'let' ('let' can be a synonym of 'permit').
'out'+'let'='OUTLET'
(Other definitions for outlet that I've seen before include "Maths relationship" , "Means or occasion for giving vent to feelings" , "Vent; shop" , "Store" , "Means of release" .)