Wary exchange is wrong (4)
I believe the answer is:
awry
'is wrong' is the definition.
(synonyms)
'wary exchange' is the wordplay.
'exchange' indicates anagramming the letters.
'wary' anagrammed gives 'AWRY'.
(Other definitions for awry that I've seen before include "Distorted, crooked" , "Crooked, askew" , "Askew, lopsided" , "Haywire" , "Out of kilter" .)