Shabby inner-city parking causes depression (5)
I believe the answer is:
slump
'depression' is the definition.
('slump' can be a synonym of 'depression')
'shabby inner-city parking' is the wordplay.
'shabby inner-city' becomes 'slum' (term for a squalid part of a city).
'parking' becomes 'p'.
'slum'+'p'='SLUMP'
'causes' acts as a link.
(Other definitions for slump that I've seen before include "Bad economic recession" , "Sudden fall as in share values" , "Sudden market drop" , "Marked decline" , "Fall heavily and limply" .)