Related Clues:

• It may be set or set off
• State of (sudden) fear
• Chili hotness unit?
• Early buzz?
• There's usually no cause for this
• *You might sleep through it
• Cellphone feature
• It might hold up a holdup
• Siren or bell
• See 9 Across
• It might stop a burglar
• Great concern
• *Frighten
• Fill with dread
• Night-table device