Adam's second son (4)
I believe the answer is:
abel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">adam's second son</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for abel that I've seen before include "Cain's victim; - Magwitch (Great Expectations)" , "done in before anyone else" , "Biblical murder victim" , "Cain slew him" , "Cain's murdered brother" .)