Related Clues:

• Covered with green creepers
• Like some walls at Harvard
• Like many walls at Princeton
• Like 11-Down's walls
• One competed in green coat?
• I was competitive with climber going up the wall?
• Old walls may be so, I contended
• Ivy covered
• One competed with climbers
• I struggled, choked by climber?
• Protected by a climber, one was in contention
• Current struggle: opening of door covered by plant
• Like the walls of an old church, maybe
• Like the outfield wall at Wrigley Field
• One competed with climbers in prominent positions