Soldier's uplifting story about love (7)

I believe the answer is:

trooper

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'soldier's' is the definition.
(trooper is a kind of soldier)

I cannot understand how the rest of the clue works.

(Other definitions for trooper that I've seen before include "Cavalry soldier" , "Cavalryman" , "He swears" , "Cavalry 21" , "Private soldier" .)

I've seen this clue in The Times.

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