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' is an anagram indicator (I've seen this in other clues).
'trade' is an anagram of '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" .)