Yellow-flowered acacia tree (6)
I believe the answer is:
mimosa
'yellow-flowered acacia tree' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mimosa that I've seen before include "Tropical tree or shrub with clusters of fragrant flowers" , "So maim with tropical shrub bearing fragrant flowers" , "Australian 15 across" , "Flower of Maoism?" , "Tropical tree with yellow flowers" .)