Incubator noise (4)
I believe the answer is:
peep
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">incubator noise</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 peep that I've seen before include "Peek" , "Furtive look" , "Chirp" , "Sly look (palindrome)" , "Look surreptitiously - through a keyhole?" .)