Chestnut

CHESTNUT

-noun

1. any of the several deciduous trees constituting the genus  Castanea, such as C. sativa (sweet  or Spanish chestnut), which produce flowers in long catkins and nuts in a prickly bur

2. the edible nut of any of these trees

3. the hard wood of any of these trees, used in making furniture, etc.

4. a. a reddish-brown to brown colour

    b. ( as adjective ): chestnut hair

5. a horse of a yellow-brown or golden-brown colour

6. a small horny callus on the inner surface of a horse's leg

7. informal . an old or stale joke

A fall treat
Hidden in a prickly prison
Chestnut