Was ballooning attacked as winter sport? (10)

I believe the answer is:

snowballed

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'attacked as winter sport?' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe you can see an association between them that I don't see?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

I've seen this clue in The Times.

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