Rich king
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rich king</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for croesus that I've seen before include "Ancient king renowned for his wealth" , "Sources for legendary rich king" , "Very rich person" , "Fabulously wealthy man" , "Rich old king" .)