The tree in the paddock (8)
I believe the answer is:
chestnut
'the tree' is the definition.
(chestnut is a kind of tree)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for chestnut that I've seen before include "Tree fruit known informally as a conker" , "Brown horse" , "''Underneath the spreading . . . . . . . . tree''" , "Item for stuffing" , "Deep reddish-brown" .)