Not bound to be licentious (5)
I believe the answer is:
loose
I believe this is a double definition.
'not bound' is the first definition.
(I've seen this before)
'licentious' is the second definition.
('loose' can be a synonym of 'licentious')
'to be' acts as a link.
(Other definitions for loose that I've seen before include "Not tight" , "poor fit?" , "Not strict" , "Water heater" , "Unattached" .)