Biting fly (4)
I believe the answer is:
gnat
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">biting fly</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 gnat that I've seen before include "Tiny biter" , "Midge, mosquito" , "small irritant" , "Sucker (if female)" , "mozzie" .)