Resounding blow (5)
I believe the answer is:
whack
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">resounding blow</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for whack that I've seen before include "Onomatopoeic blow" , "ration" , "Strike hard" , "Strike; specified share" , "Resounding blow" .)