Unspecified number evicted from stadium neighbourhood (4)
I believe the answer is:
area
'neighbourhood' is the definition.
(a neighbourhood is an urban area)
'unspecified number evicted from stadium' is the wordplay.
'unspecified number' becomes 'n' (n can represent any number).
'evicted from' suggests deleting specific letters.
'stadium' becomes 'arean' (I've seen this before).
'arean' with 'n' removed is 'AREA'.
(Other definitions for area that I've seen before include "Region; extent of a surface" , "District; plot" , "Field -- expanse" , "environs" , "Space for a specific purpose, say picnic" .)