Best-rated (1-3)
I believe the answer is:
a-one
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">best-rated</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for a-one that I've seen before include "Of the highest quality" , "First class!" .)