Perhaps slum area of Belgian city finally turns to one for food (9)
I believe the answer is:
spaghetti
'food' is the definition.
(spaghetti is a kind of food)
'perhaps slum area of belgian city finally turns to one' is the wordplay.
I cannot really understand how this works, but
'area' could be 'spa' (spa is a kind of area) and 'spa' is located in the answer.
'turns' could be 'tt' (an abbreviation for turn written twice) and 'tt' is found within the answer.
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
This explanation may well be incorrect...
'for' acts as a link.
(Other definitions for spaghetti that I've seen before include "Sort of food" , "stringy food" , "It's past eight, time for strange pasta" , "2 [PASTA]" , "Pasta twirled around a fork" .)