Acknowledge, concede (5)
I believe the answer is:
allow
I believe this is a double definition.
'acknowledge' is the first definition.
(allowing is a kind of acknowledging)
'concede' is the second definition.
(synonyms)
(Other definitions for allow that I've seen before include "Acknowledge - concede" , "Sanction" , "OK" , "Licence" , "Permit or agree" .)