Salesman always making refund (5)
I believe the answer is:
repay
'refund' is the definition.
(I know that refund can be written as repay)
'salesman always' is the wordplay.
'salesman' becomes 'rep' (sales representative).
'always' becomes 'ay' (archaic term for 'always').
'rep'+'ay'='REPAY'
'making' acts as a link.
(Other definitions for repay that I've seen before include "recompense" , "Do or give in return" , "Settle a score" , "Refund or reward" , "Reimburse" .)