Widespread destruction (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">widespread destruction</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for havoc that I've seen before include "Carnage" , "Chaotic devastation" , "Chaos, confusion" , "Ruin" , "Widespread destruction and great disorder" .)
(Other definitions for carnage that I've seen before include "Blood bath" , "Bloody slaughter and butchery" , "Mayhem" , "Savage killing of people" , "'Massacre, slaughter (7)'" .)