Argument about a right price (6)
I believe the answer is:
tariff
'price' is the definition.
(thesaurus)
'argument about a right' is the wordplay.
'argument' becomes 'tiff' (I've seen this in other clues).
'about' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'a'+'r'='ar'
'tiff' enclosing 'ar' is 'TARIFF'.
(Other definitions for tariff that I've seen before include "Menu" , "Table of fixed charges" , "Tax or duty to be paid on some imports or exports" , "Import or export duty" , "Rate" .)