A shopkeeper, a doctor and a retired salesman (6)
I believe the answer is:
draper
'a shopkeeper' is the definition.
(I've seen this before)
'a doctor and a retired salesman' is the wordplay.
'a doctor' becomes 'Dr' (abbreviation).
'and' is a charade indicator (letters next to each other).
'retired' says the letters should be written backwards.
'salesman' becomes 'rep' (sales representative).
'rep' reversed gives 'per'.
'dr'+'a'+'per'='DRAPER'
(Other definitions for draper that I've seen before include "Dealer in cloth and clothing" , "source of material?" , "Seller of textile fabrics" , "One sells sewing materials" , "Retailer of fabrics" .)