Eastern people in canvas shelters and flats (9)
I believe the answer is:
tenements
'flats' is the definition.
'eastern people in canvas shelters' is the wordplay.
'eastern' becomes 'e'.
'people' becomes 'men' (man is a kind of person).
'in' is an insertion indicator.
'canvas shelters' becomes 'tents' (I've seen this before).
'e'+'men'='emen'
'emen' going inside 'tents' is 'TENEMENTS'.
'and' acts as a link.
(Other definitions for tenements that I've seen before include "Run-down buildings housing several families" , "Large houses with a large number of families" , "Buildings rented for living in, as in city slums" , "Blocks of flats (US)" , "Large run-down buildings found in slums" .)