Perfect voice (5)
I believe the answer is:
utter
I believe this clue is a double definition.
'perfect' is the first definition.
(I know that perfect can be written as utter)
'voice' is the second definition.
(I know that voice is a more specific form of the action the utter)
(Other definitions for utter that I've seen before include "Speak; complete" , "(Of counterfeit money) put into circulation - say" , "issue" , "Say; total" , "Express in speech" .)