Related Clues:

• Sharp knock at the door
• Short, sharp knock
• Sharp sound of a door-knocker
• Sound of a door knocker
• Sharp knock as on a door
• Sharp sound of door-knocker
• A sharp knock on the door
• Sound of a knock on the door
• Knock anything so pestiferous and cheap and nasty
• Knock to pitch up the pest that's tasteless
• That's a knock, by the sound of it
• Knock for the post
• What a blow that on the door there's pestiferous rubbish
• Sleet-on-the-roof sound
• Machine gun's sounds