Dangerous bacteria (1,4)
I believe the answer is:
e coli
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dangerous bacteria</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 e coli that I've seen before include "cause of serious complaint" , "Some types of this bacterium are toxic" , "cause of ill-feeling" , "Bacterium found in the gut" , "Cause of infection" .)