Champion to stop country historian (9)
I believe the answer is:
herodotus
'historian' is the definition.
(Greek historian)
'champion to stop country' is the wordplay.
I cannot really see how this works, but
'champion' could be 'hero' (synonyms) and 'hero' is found in the answer.
'stop' could be 'dot' (I have seen 'Full stop ' mean 'dot' so perhaps 'stop' could also mean 'dot') and 'dot' is found within the answer.
'country' could be 'us' (United States) and 'us' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for herodotus that I've seen before include "Ancient Greek historian" , "Old Greek" , "Famous Greek" , "Historical pioneer" .)