Copy salesman, having story about pet (9)
I believe the answer is:
replicate
'copy' is the definition.
(thesaurus)
'salesman having story about pet' is the wordplay.
'salesman' becomes 'rep' (I've seen this before).
'having' says to put letters next to each other.
'story' becomes 'lie' (I've seen this before).
'about' means one lot of letters goes inside another.
'pet' becomes 'cat' (I have seen 'Common pet ' mean 'cat' so perhaps 'pet' could also mean 'cat'**).
'lie' going around 'cat' is 'licate'.
'rep'+'licate'='REPLICATE'
(Other definitions for replicate that I've seen before include "Copy exactly" , "Copy, reproduce" , "Make an exact copy of" .)