Plant; instrument (5)
I believe the answer is:
viola
I believe this clue is a double definition.
'plant' is the first definition.
(viola is a kind of plant)
'instrument' is the second definition.
(viola is a kind of instrument)
(Other definitions for viola that I've seen before include "whose player takes a bow" , "that provides music" , "Sebastian's twin (Twelfth Night)" , "Shakespearean role" , "Instrument slightly larger than violin and of lower pitch" .)