Polar animal's stomach? (4)

I believe the answer is:

bear

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

This could be a double definition.

'polar animal's' is the first definition.
'bear' can be an answer for 'animal's' (bear is a kind of animal). I'm not sure about the 'polar' bit.

'stomach?' is the second definition.
(both can mean to tolerate or endure)

Can you help me to learn more?

(Other definitions for bear that I've seen before include "Support, large mammal" , "Ursine animal" , "Give birth to; animal" , "Massive mammal" , "grizzly, perhaps?" .)

I've seen this clue in The Everyman puzzle in The Observer.

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