Shout of disapproval (3)
I believe the answer is:
boo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">shout of disapproval</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for boo that I've seen before include "Startling utterance" , "Exclamation of disapproval" , "Cry of disapproval as at villain" , "Disapproving jeer" , "causing surprise!" .)