Antecedent, harbinger (10)
I believe the answer is:
forerunner
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">antecedent</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that antecedent can be written as forerunner)</span><br/ ><br/ >'<span class="explanation-format__original">harbinger</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that harbinger can be written as forerunner)</span><br/ ><br/ ></span>
(Other definitions for forerunner that I've seen before include "one coming ahead" , "Precursor" .)