Prevalent in a district (7)
I believe the answer is:
endemic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prevalent in a district</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 endemic that I've seen before include "Widely prevalent" , "restricted to a particular area" , "(Of disease) regularly found in population" , "Native to a certain area" , "Belonging to a particular area" .)