Nearly phone agent over love song (7)

I believe the answer is:

calypso

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'love song' is the definition.
(thesaurus)

I don't understand the rest of the clue.

(Other definitions for calypso that I've seen before include "Improvised song of the Caribbean" , "W.Indian ballad dealing with topical events" , "Caribbean satirical song" , "West Indian ballad rhythm" , "Hostage-holding nymph" .)

I've seen this clue in The Telegraph.

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