Reach hospital in slum area (6)
I believe the answer is:
ghetto
'slum area' is the definition.
(I've seen this before)
'reach hospital in' is the wordplay.
'reach' becomes 'getto' (getting to is a kind of reaching**).
'hospital' becomes 'h'.
'in' is an insertion indicator.
'getto' enclosing 'h' is 'GHETTO'.
(Other definitions for ghetto that I've seen before include "poor part of town" , "A poor quarter of a city" , "run-down part of town" , "Poor city area" , "City quarter to which Jewish people were confined" .)