Fair returned amounts - small and large (3,3)
I believe the answer is:
not bad
'fair' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for not bad that I've seen before include "Reasonably good in negative way" , "could be OK" , "Middling (so good?)" , "fair" , "fine" .)