Mythical Greek warrior with a very loud voice (7)
I believe the answer is:
stentor
'mythical greek warrior with a very loud voice' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stentor that I've seen before include "Mythical Greek warrior with an unusually loud voice" , "Loud-voiced Greek at Troy" , "powerful speaker" , "man with loudest voice" .)