An ancestor (4)
I believe the answer is:
sire
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">an ancestor</span>' is the definition.<br/ ><span class="explanation-format__explanation">(sire is a kind of ancestor)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sire that I've seen before include "Ancestor" , "Foal's father" , "Generator" , "Rise for male parent (4)." , "Bear" .)