Disease outbreak (8)
I believe the answer is:
epidemic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">disease outbreak</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that epidemic is a type of disease outbreak)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for epidemic that I've seen before include "Widespread occurrence of a disease" , "health emergency" , "eruption" , "Outbreak of disease which spreads rapidly" , "Plague" .)