Quarrel about artist reversing price list (6)
I believe the answer is:
tariff
'price list' is the definition.
(I've seen this before)
'quarrel about artist reversing' is the wordplay.
'quarrel' becomes 'tiff' (informal term for an argument).
'about' means one lot of letters goes inside another.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'reversing' says the letters should be written backwards.
'ra' backwards is 'ar'.
'tiff' placed around 'ar' is 'TARIFF'.
(Other definitions for tariff that I've seen before include "List of prices displayed as in pub" , "Duty; table of charges" , "Tax or duty to be paid on some imports or exports" , "Duty charge" , "Price list - import tax" .)