Possible Clues:

• Not a horse performing is in shape
• Just figure how there isn't a horse to be found on this
• One over the eight without a horse on all sides
• Shape with one more side than a stop sign
• Just figure how to be horseless on this
• Just figure how there could not be any horse on this
• Figure with nine, twenty-one Dn
• Horseless on every side of one
• The figure of not a 2 down on this
• Just figure how you'd make nothing horsey on it