Billy ____ (4)
'billy' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for goat that I've seen before include "Domesticated animal supplying milk, meat and wool" , "Capricorn animal" , "Animal in zodiac" , "nanny, for example" , "beast with sharp horns" .)
'billy' is the definition.
(synonyms)
This is all the clue.