Camels ran off round antelope, small one adept at mating (6,7)

'camels ran off round' is the definition.
I know nothing about this answer so I can't judge whether this works.

'antelope small one adept at mating' is the wordplay.
I cannot really understand how this works, but
'antelope' could be 'gnu' (gnu is a kind of antelope) and 'gnu' is located in the answer.
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is present in the answer.
'one' could be 'a' (a thing is one thing) and 'a' is found in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?