Fixing pin (4)
I believe the answer is:
nail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fixing pin</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 nail that I've seen before include "Fixing spike" , "Spike, tack" , "Fixing device" , "A small steel wood pin" , "one wouldn't want in one's coffin?" .)