Infest (7)
I believe the answer is:
overrun
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">infest</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for overrun that I've seen before include "Heavily defeat" , "Invade in great numbers" , "area beyond end of airstrip" , "Exceed (cost estimate)" , "Infest - defeat totally" .)