One good at figures, perhaps? (6)
I believe the answer is:
skater
'one good' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'at figures perhaps?' is the wordplay.
I cannot quite understand how this works, but
'at' is present in the answer.
The remaining letters 'sker' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for skater that I've seen before include "Mover across ice" , "Person sliding over ice" , "Rink performer" , "Performer on ice" , "One using blades (or rollers?)" .)