Horse, cob Ron tamed (6)
I believe the answer is:
bronco
'horse' is the definition.
(bronco is a kind of horse)
'cob ron tamed' is the wordplay.
'tamed' indicates anagramming the letters.
'cob'+'ron'='cobron'
'cobron' is an anagram of 'BRONCO'.
(Other definitions for bronco that I've seen before include "Wild horse of the West" , "An unbroken mustang, bucking perhaps" , "Wild horse of the western US" , "Wild horse of W. US" , "Wild bucking horse" .)