Roman? He's rough rider (8)
I believe the answer is:
horseman
'rider' is the definition.
(someone riding a horse)
'roman? he's rough' is the wordplay.
'rough' is an anagram indicator (a rough or broken ordering of the letters).
'roman'+'hes'='romanhes'
'romanhes' with letters rearranged gives 'HORSEMAN'.
(Other definitions for horseman that I've seen before include "Male rider" , "Jockey" , "(Skilled) rider" , "Equestrian" , "mounted rider" .)