Possible Clues:

• Headgear for leading a horse
• Leather strap for leading a horse
• Rope or canvas on a horse's head
• Summer wear
• Top type
• That might put a stop to its going around your neck
• Cut the top off round the throat to make a change to the bottom of it
• Back-baring top
• Rope for leading horse
• The sort of stopper, perhaps, that will change if you take the top off