You may win one on points (8)
I believe the answer is:
argument
'you' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?
'win one on points' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'may' acts as a link.
Can you help me to learn more?
(Other definitions for argument that I've seen before include "Barney" , "Discussion - line of proof" , "Heated disagreement" , "Debate - disagreement" , "Clash of opinions" .)