Famous Greek champion to scatter us (9)
I believe the answer is:
herodotus
'famous greek' is the definition.
(I've seen this before)
'champion to scatter us' is the wordplay.
'champion' becomes 'hero' (synonyms).
'to scatter' becomes 'dot' (synonyms).
'hero'+'dot'+'us'='HERODOTUS'
(Other definitions for herodotus that I've seen before include "Famous Greek" , "Historical pioneer" , "Ancient Greek historian" , "Old Greek" .)