Possible Clues:

• Race that once had a four-minute barrier
• Imperial measure of 1.61 km
• Square __
• Miss equivalent, in some cases
• It has more than 5,000 feet
• Stephen King's "The Green ___"
• '1,760 yards (4)'
• Length unit
• Scottish way to add this extension to east wing of 1ac
• Frequent flier's unit