It weighs what's left (7)

I believe the answer is:

balance

I'm a little stuck... Click here to teach me more about this clue!

'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 Guardian and The Globe and Mail.

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