Rated badly by right businessman (6)
I believe the answer is:
trader
'businessman' is the definition.
(thesaurus)
'rated badly by right' is the wordplay.
'badly' indicates anagramming the letters.
'by' means one lot of letters go next to another.
'right' becomes 'r' (common abbreviation**).
'rated' with letters rearranged gives 'trade'.
'trade'+'r'='TRADER'
(Other definitions for trader that I've seen before include "One selling" , "Merchant ship; dealer" , "Tarred like merchant" , "Retard (anag.)" , "Dealer who buys and sells" .)