Related Clues:

• Like some walls at Harvard
• Like many walls at Princeton
• Unlike rolling stones, supposedly
• Like 11-Down's walls
• Unlike a rolling stone
• One competed in green coat?
• I was competitive with climber going up the wall?
• Like some woodland rocks
• Old walls may be so, I contended
• Like some forest floors
• Green and soft, say
• Ivy covered
• One competed with climbers
• I struggled, choked by climber?
• Protected by a climber, one was in contention