Article: It's the Met's Insiders! (3)
I believe the answer is:
the
But I can't explain it at all! Could you help me understand?
(Other definitions for the that I've seen before include "The most frequently occurring word in the Bible (and in this clue!)" , "15, 16 One given taste of own medicine" , "Last words of story" , "See 10 Across" , "and 24 Down: Similar things" .)