See cat jump off piano (5)

I believe the answer is:

ounce

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

'see cat' is the definition.
'ounce' can be an answer for 'cat' (I've seen this before). I'm unsure of the 'see' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for ounce that I've seen before include "Small amount (of old pound)" , "scrap" , "Unit of weight; cat" , "One cat" , "Snow-leopard" .)

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

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