Related Clues:

• Rarity on a rush-hour subway
• Goal for a politician
• 13C or 25A, on a plane
• "Is this ___ taken?"
• Aisle or window, e.g
• Choke and accelerator, maybe
• Part of a bus
• Head of science to take up chair
• Stadium spot
• Your chair is one
• "Please, have a ___"
• What might be hard to find on a crowded bus
• Coveted spot on a crowded bus
• Plane ticket specification
• Usher to a table