Cause a storm in a teacup (4)

I believe the answer is:

stir

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'storm in a teacup' is the definition.
'stir' can be an answer for 'storm' (thesaurus). I'm not certain of the 'in a teacup' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for stir that I've seen before include "prompt" , "jug" , "Prison - mix" , "Cause to move in slangy prison" , "Whisk, blend" .)

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

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