Word ignored when alphabetizing (3)
I believe the answer is:
the
'word ignored when alphabetizing' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for the that I've seen before include "and 24 Down: Similar things" , "The most frequently occurring word in the Bible (and in this clue!)" , "French drink" , "Last words of story" , "15, 16 One given taste of own medicine" .)