Upright character, a snob, rejected oriental art (6)
I believe the answer is:
'oriental art' is the definition.
'bonsai' can be an answer for 'art' (I have seen 'Japanese art' mean 'bonsai' so perhaps 'art' could also mean 'bonsai'). I am unsure of the 'oriental' bit.
'upright character a snob rejected' is the wordplay.
'upright character' becomes 'I' (vertical letter of the alphabet).
'rejected' shows that the letters should be reversed in order.
'iasnob' backwards is 'BONSAI'.
Can you help me to learn more?
(Other definitions for bonsai that I've seen before include "Art of dwarfing shrubs" , "Dwarf tree cultivation" , "specimen with restricted roots?" , "Japanese art of growing dwarf trees" , "Japanese art of growing dwarfed trees" .)