A nip from a nipper (3)

I believe the answer is:

tot

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'nipper' is the definition.
(I know that tot is a type of nipper)

I cannot understand how the rest of the clue works.

(Other definitions for tot that I've seen before include "Small measure for a small child" , "Nip" , "Sum for the little one" , "finger, possibly" , "Add up, aggregate" .)

I've seen this clue in the Evening Standard.

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