Upright character, a snob, rejected oriental art (6)
I believe the answer is:
bonsai
'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.
'i'+'a'+'snob'='iasnob'
'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" .)