Not in; less left in. Supplies larger quantities than others (3-5)

'supplies larger quantities than others' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'not in less left' is the wordplay.
I cannot really see how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
'left' could be 'l' (common abbreviation) and 'l' is found within the answer.
an anagram of 'less' is 'sels' which is within the left over letters.
The remaining letters 'ut' 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).

'in' acts as a link.

Can you help me to learn more?