Treacherous top lawyer used wire to listen in (6)

I believe the answer is:

earwig

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'to listen in' is the definition.
(earwig can mean to secretly listen to something)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for earwig that I've seen before include "An insect; to eavesdrop (slang)" , "Clawed insect" , "Tap" , "Aural appendage and head covering for an insect" , "court" .)

I've seen this clue in The Irish Times.

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