The sound of thunder? (4)
I believe the answer is:
clap
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the sound of thunder?</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 clap that I've seen before include "Audibly show approval" , "Applaud in manual way" , "cheer" , "Make sound of applause" , "Pat" .)