Vagrant in hedge made a beastly sound (7)
I believe the answer is:
neighed
'made a beastly sound' is the definition.
(to neigh is to make a horse sound)
'vagrant in hedge' is the wordplay.
'vagrant' is an anagram indicator (I've seen this in other clues).
'in'+'hedge'='inhedge'
'inhedge' anagrammed gives 'NEIGHED'.
(Other definitions for neighed that I've seen before include "Heeding (anag)" , "Cried" , "sounded "horsey"" , "Made a sound like a horse" , "how Arab, for example, sounded" .)