Neigh (6)
I believe the answer is:
whinny
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">neigh</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that neigh can be written as whinny)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for whinny that I've seen before include "animal noise?" , "Horse's cry" , "A horse may do it" , "High-pitched neigh" , "Gentle or joyful neigh" .)