How delivering Pooh's parcels can be exerting? (8,2,4)

I believe the answer is:

bringing to bear

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

'exerting?' is the definition.
The definition and answer can be both to do with social activities as well as being present participle verbs.
Maybe you can see an association between them that I don't see?

'how delivering pooh's parcels can be' is the wordplay.
I cannot really see how this works, but
'be' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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