The remaining six balls, evidently not needed (4,4)
I believe the answer is:
left over
'the remaining' is the definition.
(I've seen this before)
'six balls evidently not needed' is the wordplay.
I cannot really see how this works, but
'balls' could be 'over' (I've seen this in other clues) and 'over' is present in the answer.
The remaining letters 'left' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for left over that I've seen before include "Surplus" , "Not used up" , "Spare, remaining" .)