Possible Clues:

• One makes jokes better with the ultimate in scabrous content
• Customer outside entrance to shop, a jocular type
• Verbal joker
• Setter occasionally having 'regular' about stumped at first?
• Person gambling to arrest southern joker
• One who plays on words
• Seller initially taken in by customer, a joker
• Ordinary patron's butt of gags halfway through for comedian
• Last of clues penned by better user of wordplay
• One making jokes better son admitted