Indian city taken in by obscure plan (7)
I believe the answer is:
diagram
'plan' is the definition.
(I've seen this before)
'indian city taken in by obscure' is the wordplay.
'indian city' becomes 'agra' (I've seen this in another clue).
'taken in by' means one lot of letters goes inside another.
'obscure' becomes 'dim' (both can mean dark).
'agra' going into 'dim' is 'DIAGRAM'.
(Other definitions for diagram that I've seen before include "I'm a drag (anag)" , "Simplified representation" , "A grid, Ma? (Anag)" , "Schematic representation" , "Chart" .)