Hybrid charged by learner daughter gets messed up (6)

I believe the answer is:

mulled

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'messed up' is the definition.
Although both the answer and definition are past participle verbs, I don't understand how they can define each other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for mulled that I've seen before include "Warm, spiced (wine)" , "Of wine, heated with sugar and spices" , "Pondered" .)

I've seen this clue in The Times and The Sunday Times.

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