Central part (4)
I believe the answer is:
core
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">central part</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 core that I've seen before include "Heal" , "Central or most important part of something" , "Essence" , "Central zone" , "essential element" .)