Heard what's round my neck is a rum concoction (3,3)

I believe the answer is:

mai tai

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'rum concoction' is the definition.
(I've seen this in another clue)

I don't understand how the remainder of the clue works.

(Other definitions for mai tai that I've seen before include "drink?" , "Cocktail" .)

I've seen this clue in The Times.

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