Permission to pull out (5)
I believe the answer is:
leave
I believe this is a double definition.
'permission' is the first definition.
(leave is permission or authorisation)
'pull out' is the second definition.
(pull out can mean to leave or vacate an area)
'to' acts as a link.
(Other definitions for leave that I've seen before include "Time off; go" , "Permission (to take holidays?)" , "Don't touch" , "Depart on work holiday?" , "Depart - on office holidays?" .)