Possible Clues:

• Painter's redone door panel having missed bit in middle
• "Da Vinci Code" name
• - - da Vinci
• A long time being kept by fat old Italian
• DiCaprio of "The Departed"
• Thriller writer has nothing on Renaissance man
• A Teenage Mutant Ninja Turtle
• Feline Capulet
• So-called code genius?
• - Da Vinci, Italian painter, engineer, sculptor