Small grouse (3)
I believe the answer is:
nit
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small grouse</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 nit that I've seen before include "Idiot, ass" , "Muggins" , "Stupid person; egg" , "Cause of much head-scratching" , "Parasite's egg made of tin" .)