Imitate a donkey (4)
I believe the answer is:
bray
'imitate a donkey' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bray that I've seen before include "Cry like a donkey" , "Neigh" , "Donkey call" , "Donkey's noise" , "The Vicar of --; heehaw" .)