He savagely attacked Roman civilisation (6)
I believe the answer is:
attila
'he savagely attacked roman civilisation' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is all the clue.
Can you help me to learn more?
(Other definitions for attila that I've seen before include "Hunnish conqueror" , "Hunnish ruler" , "Great king of the huns" , "conquered Europe" , "Warrior" .)