Harry turned up carrying a plant (6)
I believe the answer is:
yarrow
'plant' is the definition.
(yarrow is a kind of plant)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for yarrow that I've seen before include "Creeping plant, also called milfoil" , "Wild aromatic plant" , "Strong-scented plant, rhymes with not wide" , "'Achillea millefolium'" , "Creeping perennial plant, used in herbal medicine" .)