Cheating -- could be attractive keeping notes exchanged (10)
I believe the answer is:
dishonesty
'cheating' is the definition.
(thesaurus)
'attractive keeping notes exchanged' is the wordplay.
'attractive' becomes 'dishy' (similar in meaning).
'keeping' indicates putting letters inside.
'exchanged' indicates anagramming the letters.
'notes' anagrammed gives 'onest'.
'dishy' placed around 'onest' is 'DISHONESTY'.
'could be' is the link.
(Other definitions for dishonesty that I've seen before include "Graft" , "Crookedness" , "Untrustworthiness, insincerity" , "Bad behaviour" , "fraud" .)