Fret over a climbing plant (6)

I believe the answer is:

yarrow

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'plant' is the definition.
(yarrow is a kind of plant)

I cannot understand how the rest of the clue works.

(Other definitions for yarrow that I've seen before include "Pungent plant" , "Hedgerow plant" , "Creeping perennial plant, used in herbal medicine" , "bloomer" , "'Achillea millefolium'" .)

I've seen this clue in The Telegraph.

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