Possible Clues:

• Batter section of fortification
• Barricade in ''The Star-Spangled Banner''
• Perhaps a bit sheepish to be on the defensive
• Defensive wall or mound
• Drive forcefully into separate defensive wall
• The sort of a bit of mutton that might help one if one got an attack
• Military protection
• The bit of the sheep that's defensive
• For the defence, that's enough to make one a bit sheepish
• Pain-relieving drug