Plant borders of Chinese territory in East (9)
I believe the answer is:
celandine
'plant' is the definition.
(celandine is a kind of plant)
'borders of chinese territory in east' is the wordplay.
'borders of' suggests removing the centre.
'territory' becomes 'land' (land is a kind of territory**).
'east' becomes 'e' ('E' can be a synonym of 'east').
'chinese' with its middle taken out is 'ce'.
'ce'+'land'+'in'+'e'='CELANDINE'
(Other definitions for celandine that I've seen before include "Land niece with the swallowwort." , "... one blooming" , "Flowering plant - decennial (anag)" , "Plant of buttercup family" .)