Possible Clues:

• The writer's prudish, having exposed adult book licence
• One foreign politician on the edge finds a dull routine upsetting and 20 across is responsible for sanctioning it
• Official approval
• The setter's punctilious nature pointlessly requiring permission
• Troublemaker, Irish revolutionary, with age almost getting approval
• Licence in publishing
• Licence to print a book
• A certain licence in publishing
• Naughty kid beginning to reform, one adult almost? Approval shown
• Licence for devil to take one not quite ripe