Possible Clues:

• A lot of worms pause for thought, being previously exhibited in the 15 square 4
• Backward clergyman only afterwards told of artist
• Painter of 18
• Dutch painter, 1673-75
• Dutch master
• The cleric is up to sounding a mere follower of Jan for art
• Churchman backing up mere slapdash painter
• 'View of Delft' painter
• Artist is right - objectively, I got into change of direction
• 'Dutch painter, noted for his use of light (7)'