Possible Clues:

• One who sticks at his job and mails his account?
• Advertising worker, one who sticks up for their employer?
• One who pastes up adverts on hoardings
• One's work's stuck up, as William in the reign of Charles III?
• One pasting up advertisements
• He sticks up for his employer
• Hoarding may be his sticking-point
• Hoarding coverage? This could be his occupation
• He sticks up for his employer, one who mails accounts
• One who needs notice before carrying out a stick-up?