Utter prerogative (5)
I believe the answer is:
right
This clue is a double definition.
'utter' is the first definition.
(both can mean complete or total)
'prerogative' is the second definition.
(a prerogative is a legal right)
(Other definitions for right that I've seen before include "One has a claim to be correct" , "Morally defensible" , "Morally good; rectify" , "OK?" , "blue, politically" .)