Musical livewire (9)

I believe the answer is:

conductor

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'musical' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for conductor that I've seen before include "Bandleader" , "Leader of a group of musicians" , "Musician" , "Director - band leader" , "Train guard" .)

I've seen this clue in The Globe and Mail.

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