Neutral vowel (5)
I believe the answer is:
schwa
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">neutral vowel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for schwa that I've seen before include "Indistinct sound" , "Unstressed vowel (phonetics)" , "Stress-free sound" , "Uh' sound" , "sound unstressed" .)