South American training to race across Roman road (8)
I believe the answer is:
peruvian
'south american' is the definition.
(Peruvian is an example)
'training to race across roman road' is the wordplay.
'training' becomes 'pe'.
'to race' becomes 'run' (running is a kind of racing).
'across' indicates putting letters inside.
'roman road' becomes 'via' (I've seen this before).
'run' placed around 'via' is 'ruvian'.
'pe'+'ruvian'='PERUVIAN'
(Other definitions for peruvian that I've seen before include "Eg, native of Lima" , "Nationality of citizen of Lima" , "Of someone from Lima, say" , "Paddington's nationality" , "Certain South American" .)