Admirer's Cockney origin announced (4)

I believe the answer is:

beau

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'admirer's' is the definition.
(I've seen this before)

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

(Other definitions for beau that I've seen before include "Dapper fellow" , "Lover boy" , "Male admirer; dandy" , "Dandy - boyfriend" , "An old-fashioned boy friend like Brummell" .)

I've seen this clue in The Sun.

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