It weighs what's left (7)

I believe the answer is:

balance

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'what's left' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for balance that I've seen before include "A steady position as on scales" , "Surplus" , "Equipoise" , "It weighs - the remainder" , "Rest" .)

I've seen this clue in The Globe and Mail and The Guardian.

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