Ferocious, savage (6)
I believe the answer is:
fierce
I believe this is a double definition.
'ferocious' is the first definition.
(I know that ferocious can be written as fierce)
'savage' is the second definition.
(I know that savage can be written as fierce)
(Other definitions for fierce that I've seen before include "Menacing" , "Ferocious, savage" , "Vehement, furious" , "Violent in temper or manner" , "Intensely aggressive" .)