Equine hybrid

HINNY

This offspring of a male horse and a female donkey is smaller than its mule cousin but shares a similar stubborn streak.

"Equine hybrid" refers to a cross between a horse and a donkey, and the answer is "hinny." Unlike a mule (which comes from a male donkey and a female horse), a hinny is the offspring of a male horse and a female donkey. The clue is straightforward—no wordplay—just a direct definition for a less common but well-known animal hybrid.