Thunder sound (4)
I believe the answer is:
clap
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thunder sound</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 "Pat" , "A meeting of hands" , "Express approbation with the hands" , "Strike hands together to applaud" , "Audibly show approval" .)