These trees have no great variety (6)
I believe the answer is:
bonsai
'variety' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for bonsai that I've seen before include "Mini-tree growing" , "small growth" , "specimen with restricted roots?" , "Japanese art of growing dwarf trees" , "Bosnia (anag.)" .)