Closest family member (4,2,3)
I believe the answer is:
next of kin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">closest family member</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that closest family member can be written as next of kin)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for next of kin that I've seen before include "Nearest relatives" , "Closest living relative" , "One's closest relatives" , "nearest people" .)