Possible Clues:

• Sounds as if there's a clear sky tonight, but that will come to an end
• It's in it, 21 down
• Limited, not unbounded
• Having limits in space or time
• Restricted - having limits
• What you have to pay about it will come to an end
• It comes to an end in a fine way
• What's so good about it is that it comes to an end
• Circumscribed
• It has an end in it in it