Part of a chain (4)
I believe the answer is:
link
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">part of a chain</span>' is the definition.<br/ ><span class="explanation-format__explanation">('link' is part of 'chain')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for link that I've seen before include "website feature" , "Relationship; intertwine" , "Join; loop in a chain" , "Join together" , "section of chain" .)