Possible Clues:

• Circle globe to enter small valley which visitors use
• Avon commercial sound
• It indicates you've arrived -- don't knock it!
• Some salesmen must use this or be splitting small figure
• What visitors ring
• Alternative to a knocker
• What one rings to be let in
• It's rung by visitors
• Model snatches bejewelled item, heading for engagement ring here
• Front door ringer