Related Clues:

• Clot
• Utter doofus
• Palm Sunday transportation
• Low-emission transport?
• Pack bearer
• Beast that bore Balaam
• Horse's wild cousin
• Subject of many a 59-Down photo
• Clown handle
• Onager, e.g.
• One may be kicked for motivation
• Paragon of stubbornness
• Equine animal
• Mule's parent
• Pumpkinhead