Assessed trade incorrectly (5)
I believe the answer is:
rated
'assessed' is the definition.
(rating is a kind of assessing)
'trade incorrectly' is the wordplay.
'incorrectly' indicates an anagram (I've seen this in other clues).
'trade' anagrammed gives 'RATED'.
(Other definitions for rated that I've seen before include "Estimated the value or assigned a ranking" , "Assessed; merited" , "Assessed, valued" , "Adjudged" , "Graded, ranked" .)