Sensitive plant (6)
I believe the answer is:
mimosa
'sensitive plant' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mimosa that I've seen before include "Yellow-flowered acacia tree" , "One growing sensitive" , "Tropical shrub with yellow flowers" , "Sensitive tree or shrub with globular clusters of yellow flowers" , "Australian 15 across" .)