Dwarfed ornamental tree or shrub (6)
I believe the answer is:
bonsai
I believe this clue is a double definition.
'dwarfed ornamental tree' is the first definition.
(I've seen this in another clue)
'shrub' is the second definition.
(I have seen 'Japanese shrub' mean 'bonsai' so perhaps 'shrub' could also mean 'bonsai')
(Other definitions for bonsai that I've seen before include "Japanese craft of growing miniature trees" , "Dwarf tree cultivation" , "Art of dwarfing shrubs" , "Japanese method of cultivating miniature trees" , "Japanese art of growing miniature trees" .)