Thesaurus creator (5)
I believe the answer is:
roget
'thesaurus creator' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for roget that I've seen before include "man of many words" , "Thesaurus writer" , "Thesaurus constructor" , "Thesaurus maker" , "English physician and thesaurus compiler, d. 1869" .)