A dismissive thing to say (2,4)

I believe the answer is:

go home

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'say' is the definition.
Although both the answer and definition are verbs in their base form, I don't understand how one could define the other.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for go home that I've seen is " Hit target".)

I've seen this clue in the Evening Standard.

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