Crossword Genius

Couples in scar unit call for bruise application (6)

Ross

I believe the answer is:

arnica

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'application' is the definition.
(plant used as a medical application)

I don't understand the rest of the clue.

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(Other definitions for arnica that I've seen before include "Tincture of mountain tobacco, good for bruises, etc" , "flowering plant" , "Tincture for treating bruises" , "medicinal preparation" , "Herb used for treating bruises" .)

I've seen this clue in The Telegraph.
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