Related Clues:

• Half the people on earth smell
• American through to final of slam gets beat
• Drone; tap idly
• Buzz; stink
• Cut digit catching front of remote drone
• Half of them rumble with a rhythmic sound
• Tap a beat with fingers
• Well-tuned engine output
• Sing with mouth closed
• Drone or buzz
• Vibration sound
• Operate smoothly
• Continuous rhythmic humming sound
• Cut thread ... half of which lost by hesitating?
• Tone heard rhythmically, usually monotonous primarily