Where the Taj Mahal is depicted in diagrams (4)
I believe the answer is:
agra
'where the taj mahal is' is the definition.
(I've seen this in another clue)
'depicted in diagrams' is the wordplay.
'depicted in' indicates a hidden word.
'AGRA' is hidden within 'diagrams'.
(Other definitions for agra that I've seen before include "Not tight" , "Taj Mahal location" , "Eastern city" , "North Indian city, former capital of the Mogul empire" , "vicinity of mausoleum" .)