An arachnid (6)
I believe the answer is:
spider
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">an arachnid</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that spider is a type of arachnid)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for spider that I've seen before include "potter's accessory?" , "A crawler" , "Webster" , "Prised open the arachnid" , "Web developer" .)