Fake news in salesman's returns (7)
I believe the answer is:
replies
'returns' is the definition.
'fake news in salesman's' is the wordplay.
'fake news' becomes 'lie'.
'in' is an insertion indicator.
'salesman's' becomes 'reps'.
'lie' going inside 'reps' is 'REPLIES'.
(Other definitions for replies that I've seen before include "Reacts verbally" , "Responds" , "Answers" .)