thesaurus entry (7)
I believe the answer is:
synonym
'thesaurus entry' is the definition.
(a thesaurus lists words with their synonyms)
This is the entire clue.
(Other definitions for synonym that I've seen before include "Equivalent word" , "Word that can replace another in context" , "Word that can be exchanged for another" , "text with similar import" , "Substitute brought in for a term" .)