Its promoters will raise no obstacle of course (4,4)
I believe the answer is:
flat race
'course' is the definition.
Both the answer and definition are singular nouns.
Maybe there's an association between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for flat race that I've seen before include "event" , "The rush, of course" , "St Leger, for instance" , "Derby, for example" , "not hurdled" .)