Related Clues:

• Stand-up delivery
• "Silence"
• Curtail one's freedom of speech
• Be silent
• Keep under wraps
• Repress
• 'Don't say a word!'
• Ideal for engines and audio equipment
• Stand-up standard
• Trumpeter's muffler
• Delay, in a way
• ''Be still!''
• Sordino, e.g.
• Keep concealed, with 'up'
• 'Put a sock in it!'