Related Clues:

• Fence opening
• Fence crossover
• Vegas machine opening
• Fence feature, perhaps
• Subway-entrance barrier
• Hole in a vending machine
• Coin destination, sometimes
• Vegas staple
• Hole in a Vegas machine
• Mail drop, e.g.
• Mailbox opening
• Word with mail or time
• Tab's counterpart
• Fence-crossing aid
• Allocated time