Related Clues:

• Envelope opening
• Thing in a vending machine
• Machine's opening for coins
• Piggy bank's opening
• Opening for mail or coins
• Hole (for a coin?)
• Hole to fill
• Allotted time
• __ car: toy racer
• Coin opening; place with precision
• Mailbox hole
• Coin-op hole
• Blank on a sign-up sheet
• Appointment space
• __ machine