Spiky character flat out on road? (8)
I believe the answer is:
hedgehog
'flat out on road?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'spiky character' is the wordplay.
I cannot really understand how this works, but
'character' could be 'he' (he is a kind of character) and 'he' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hedgehog that I've seen before include "Spiny animal" , "Prickly garden animal" , "Prickly beast" , "Prickly creature" , "Small prickly insectivore" .)