One who succeeds (4)
I believe the answer is:
heir
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one who succeeds</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 heir that I've seen before include "One hoping to succeed" , "One likely to succeed" , "Treasured family possession" , "one's to inherit throne!" , "One who succeeds" .)