Related Clues:

• Word with master or waiter
• Lucille Ball, notably
• Brain
• It has plenty of brains
• Administrator
• Beer foam
• Lettuce unit
• Nail part
• See 48 Across
• Bowler's place
• Beer feature
• Person in charge
• Cranium
• President
• Word that can precede the starts of 17-, 27-, 45- and 60-Across and 11- and 34-Down