Ferocious, brutal (6)
I believe the answer is:
savage
I believe this clue is a double definition.
'ferocious' is the first definition.
(synonyms)
'brutal' is the second definition.
(synonyms)
(Other definitions for savage that I've seen before include "Cruel, vicious" , "Uncivilized" , "Fierce, cruel" , "Wild, untamed" , "Wild and menacing" .)