Release Blue Berets with roles on way north (7)
I believe the answer is:
unstrap
'release' is the definition.
(to release from straps)
'blue berets with roles on way north' is the wordplay.
'blue berets' becomes 'UN' (United Nations peacekeepers).
'with' says to put letters next to each other.
'roles' becomes 'parts' ('part' can be a synonym of 'role').
'on way north' says the letters should be written in reverse (in a down clue, letters go up or 'north').
'parts' back-to-front is 'strap'.
'un'+'strap'='UNSTRAP'
(Other definitions for unstrap that I've seen before include "Remove fastenings from" , "Release" , "loose" , "Loosen tie" .)