Salesman with shoddy lines hard to replace (9)
I believe the answer is:
replenish
'replace' is the definition.
(thesaurus)
'salesman with shoddy lines hard' is the wordplay.
'salesman' becomes 'rep' (I've seen this before).
'with' means one lot of letters go next to another.
'shoddy' is an anagram indicator (I've seen this in other clues).
'hard' becomes 'h'.
'lines' anagrammed gives 'lenis'.
'rep'+'lenis'+'h'='REPLENISH'
'to' is the link.
(Other definitions for replenish that I've seen before include "Refill or make complete again" , "Fill again, renew a supply" , "Help siren (anag) - fill up again" , "Restore" , "Stock up again" .)