Permission to go (5)
I believe the answer is:
leave
This clue is a double definition.
'permission' is the first definition.
(leave is permission or authorisation)
'go' is the second definition.
(go can mean to depart or leave)
'to' is the link.
(Other definitions for leave that I've seen before include "Relinquish - holiday" , "Permission (to take holidays?)" , "Permission - time off" , "Something taken by those withdrawing" , "Furlough" .)