Permits expressions of pain, after all (6)
I believe the answer is:
allows
'permits' is the definition.
('allow' can be a synonym of 'permit')
'expressions of pain after all' is the wordplay.
'expressions of pain' becomes 'ows' ('ow' is an expression of pain).
'after' says to put letters next to each other.
'ows' after 'all' is 'ALLOWS'.
(Other definitions for allows that I've seen before include "Tolerates" , "Permits, lets" , "Permits or agrees" , "Permits to do something" , "Gives permission" .)