Thesaurus compiler (5)
I believe the answer is:
roget
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thesaurus compiler</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 roget that I've seen before include "lexicographer" , "Thesaurus creator" , "English doctor, compiler of a thesaurus, d. 1869" , "Thesaurus maker" , "English physician and thesaurus compiler, d. 1869" .)