Related Clues:

• Zero, e.g.
• Racing circuit
• Like one White House office
• Not quite a circle
• Lionel train layout, maybe
• Cartouche's shape
• Elliptical shape
• Oviform
• Elliptical track
• Picture frame shape
• George's office
• NASCAR track
• Like some earrings
• Like 'O'
• Amphitheater shape