Salesman keeping a cut (4)
I believe the answer is:
reap
'cut' is the definition.
(I've seen this before)
'salesman keeping a' is the wordplay.
'salesman' becomes 'rep' (sales representative).
'keeping' means one lot of letters goes inside another.
'rep' placed around 'a' is 'REAP'.
(Other definitions for reap that I've seen before include "Save harvest, glean" , "Glean or cut as harvest" , "Cut the corn" , "Use a scythe" , "Derive as a reward" .)