Point out a horse (5)
I believe the answer is:
pinto
'a horse' is the definition.
(I know that pinto is a type of horse)
'point out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'point' anagrammed gives 'PINTO'.
(Other definitions for pinto that I've seen before include "Spotted or piebald horse" , "patchy horse" , "A piebald pony" , "Mount" , "Piebald horse (US)" .)