Get moving to ensure you’re prepared for an attack (8)

I believe the answer is:

mobilise

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'get' is the definition.
Both the answer and definition are verbs in their base form.
Maybe there's an association between them I don't understand?

I can't explain the remainder of the clue.

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(Other definitions for mobilise that I've seen before include "Make ready for action, troops for war perhaps" , "Marshal" , "18d [GET READY]" , "prepare for active service" , "rally" .)

I've seen this clue in the Evening Standard.

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