Complete discretion or authority (5,7)
I believe the answer is:
carte blanche
This clue is a double definition.
'complete discretion' is the first definition.
(I've seen this before)
'authority' is the second definition.
(I know that carte blanche is a type of authority)
(Other definitions for carte blanche that I've seen before include "Complete discretion" , "Free hand" , "absolute authority" , "free rein" , "Unrestricted authority" .)