Medicinal root (7)
I believe the answer is:
ginseng
'medicinal root' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ginseng that I've seen before include "Plant tuber credited with tonic properties" , "Aromatic root with medicinal powers" , "Plant, medicinal forked root" , "Root used in Chinese medicine" , "Tuber with tonic effect" .)