Salesman is not to put on new coat (7)
I believe the answer is:
repaint
'put on new coat' is the definition.
(I've seen this before)
'salesman is not' is the wordplay.
'salesman' becomes 'rep' (sales rep).
'is not' becomes 'ain't' ('ain't' is a non-standard form of 'isn't').
'rep'+'aint'='REPAINT'
'to' acts as a link.
(Other definitions for repaint that I've seen before include "To provide fresh cover" , "put on new coat" , "put on another coat" .)