Study of heredity (8)
I believe the answer is:
genetics
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">study of heredity</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for genetics that I've seen before include "Study of inherited characteristics" , "Branch of biology" , "Science of heredity" , "The study of biological heredity" , "The scientific study of heredity" .)