Hunts, etc, ruined horse (8)
I believe the answer is:
chestnut
'horse' is the definition.
(chestnut is a kind of horse)
'hunts etc ruined' is the wordplay.
'ruined' indicates an anagram.
'hunts'+'etc'='huntsetc'
'huntsetc' is an anagram of 'CHESTNUT'.
(Other definitions for chestnut that I've seen before include "Tree fruit known informally as a conker" , "Old story" , "Stale joke or cliche" , "Horse coat colour" , "Old joke - edible kernel" .)