Two-dimensional chart artist turned over (6)
I believe the answer is:
planar
'two-dimensional' is the definition.
('planar' can be similar in meaning to 'two-dimensional')
'chart artist turned over' is the wordplay.
'chart' becomes 'plan' (I've seen this before).
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'turned over' says the letters should be written in reverse.
'ra' backwards is 'ar'.
'plan'+'ar'='PLANAR'
(Other definitions for planar that I've seen before include "Ran lap (anag) - flat" , "Lying in a flat surface" , "12 [TWO DIMENSIONAL]" , "In two dimensions" .)