Related Clues:

• Sold-out sign abbr.
• Success sign
• Unlikely sign at a 54-Across
• Sign of overfilling
• "No seats" sign
• Sign at a hit
• Great sign for a Broadway angel
• No seats sign, briefly
• Sign for a Broadway hit
• Hit notice?
• Hit sign?
• Good sign on B'way
• Sign at packed theaters
• Marquee letters
• Box off. sign