Related Clues:

• Feature of some zoos
• Alternative to a fence
• Protective ring
• Water-filled trench
• 'Cabaret' director Bob
• See 65-Across
• Choreographer Bob
• Castle's protective feature
• Castle's protector
• Palace guard?
• Broadway's Bob
• Broadway dance hit of 1999
• Castle surrounding
• A drawbridge spans it
• Middle Ages defense