Related Clues:

• Horizontal length of timber, stone, etc along the bottom of an opening
• Goes around side of hall for the flowerpot
• Son unwell -- one lies horizontally
• Pie perch, perhaps
• Piece under a door
• Window box support
• Base of a window
• It's under the window
• Horizontal intrusion of igneous rock between sedimentaries, as in much of Hadrian's Wall
• Place for potted herbs
• Sun tea brewing spot
• Place to set a candle, maybe
• Slab at foot of window
• Window or door part
• The lower sash rests on it