Large-headed nail (4)
I believe the answer is:
stud
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large-headed nail</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for stud that I've seen before include "What makes shoe skidproof" , "Farm for breeding horses" , "Collar fastener or horse farm" , "Part of a football boot" , "Form of poker game" .)