Tracey —, artist (4)
I believe the answer is:
emin
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">tracey</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(Tracey Emin the British artist)</span><br/ ><br/ >'<span class="explanation-format__original">artist</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for emin that I've seen before include "Artist" , "See 24 Across" .)