Permissible to run away (5)
I believe the answer is:
legit
I believe this is a double definition.
'permissible' is the first definition.
(thesaurus)
'run away' is the second definition.
(as in 'leg it')
'to' is the link.
(Other definitions for legit that I've seen before include "In accordance with the law (abbr)" , "Authorised" , "Conforming to the law" , "not unlawful" , "Such theatre" .)