Related Clues:

• See 52-Across
• The six of ''Little Nellie Kelly''
• Hollow center?
• Racetrack shapes
• Berlin output
• Cousins of monorails
• Deformed circles
• Tiger's rival Ernie
• Trains overhead
• Urban transportation
• The 40 in a 'top 40'
• 2002 British Open champion
• Ernie of the PGA
• Railways with a view
• Subway relatives