Possible Clues:

• Hard graft never inspires a writer in the advertising industry
• Catchphrase inventor having drunk one's lager
• Genre also difficult for advertising worker
• Rocker seized by one looking to influence opinions?
• Advertising professional in general so phoney
• Ad agency specialist
• Inventor of memorable phrases for campaigning
• Work hard on article always as one promoting a cause
• Hyper?
• Propagandist's hard work, always penning article