Business rated incorrectly (5)
I believe the answer is:
trade
'business' is the definition.
(I know that trade is a type of business)
'rated incorrectly' is the wordplay.
'incorrectly' is an anagram indicator (I've seen this in other clues).
'rated' is an anagram of 'TRADE'.
(Other definitions for trade that I've seen before include "groundsman?" , "Dealings, business" , "Rated (anag.)" , "Buying/selling of goods" , "Barter, do business" .)