Piece of a chain (4)
I believe the answer is:
link
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">piece of a chain</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for link that I've seen before include "A chain is as strong as its weakest one" , "Means of connection between things" , "Item of mail" , "Connect" , "Make a connection" .)