Related Clues:

• Roaring group
• Hit show abbr.
• Sold-out theater letters
• 'No seats' letters
• Sign scalpers adore
• Packed, in a way: abbr.
• Sold out sign
• Sold-out sign abbr.
• Success sign
• Unlikely sign at a 54-Across
• Sign of overfilling
• "No seats" sign
• Marque letters
• Sign at a hit
• Great sign for a Broadway angel