Japanese art of growing dwarf plants (6)
I believe the answer is:
bonsai
'japanese art of growing dwarf plants' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bonsai that I've seen before include "Little Japanese growth" , "Japanese craft of growing dwarf trees" , "Japanese art of growing dwarf plants" , "Very little tree" , "Tiny Japanese tree" .)