Hinged fastener (4)
I believe the answer is:
hasp
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hinged fastener</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 hasp that I've seen before include "Hinged metal fastener" , "part of a lock" , "Door latch" , "Fastening plate, clasp" , "Hinged fastening" .)