Hee-hawed (6)
I believe the answer is:
brayed
'hee-hawed' is the definition.
('bray' can be a synonym of 'hee-haw')
This is all the clue.
(Other definitions for brayed that I've seen before include "Made noise like donkey" , "Made sound like donkey" , "Hee-hawed" , "Laughed like a donkey" , "made a beastly noise" .)