Possible Clues:

• High-rise convenience, perhaps
• Lift attendant remaining silent?
• Elevator for transporting food
• Can it raise soufflés, for example, noiselessly?
• High-rise convenience
• Food table, lift
• Thick fluid coating one restaurant fitting
• One offered a lift to the course - I wouldn't say if I was expecting anything
• Server who won't take tips?
• Silent servant given promotion from the kitchen