Wacky ideas must get valued roughly (12)

I believe the answer is:

guesstimated

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'valued roughly' is the definition.
Although both the answer and definition are past participle verbs, I don't see how they can define each other.

'wacky ideas must get' is the wordplay.
'ideas must get' can be anagrammed to 'GUESSTIMATED'.
But, I'm not sure how this is indicated.

Can you help me to learn more?

I've seen this clue in The Times.

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