Wingless parasitic insect (5)
I believe the answer is:
louse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wingless parasitic insect</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for louse that I've seen before include "scum" , "Human parasite" , "Parasite; nasty person" , "Wingless parasite" , "Nit" .)