Possible Clues:

• Appear in play on time as Wall, a low sort
• Low wall round edge of balcony
• Bedding in oil plant, gently press down low bank
• Mimic in part of breastwork
• Primate sheltered by section of earthwork
• Animal in a role that gives limited protection
• Wall on edge of roof
• Low barrier edging balcony
• Bridge safety feature
• Talk about a favourite defence