"Pipe down!"
(Another definition for shush that I've seen is " Interjection for keep quiet, don't make noise".)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pipe down</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for hush that I've seen before include "Make (someone) quiet" , "Sudden descent of silence" , "Soothe" , "Noiselessness" , "(Call for) quiet" .)