Hee-haw (4)
I believe the answer is:
bray
'hee-haw' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for bray that I've seen before include "Donkey's call; its vicar trimmed" , "Donkey's cry" , "Cry of animal" , "Donkey's heehaw" , "where musical vicar lived" .)