Operatic villian? (3)

I believe the answer is:

rat

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'villian?' is the definition.
I can't tell whether this definition defines the answer.

'operatic' is the wordplay.
'RAT' is hidden in amongst the letters.
But, I'm not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for rat that I've seen before include "Contemptible person" , "Long-tailed rodent" , "Unpopular rodent" , "Treacherous person" , "person doing shopping" .)

I've seen this clue in the Evening Standard.

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