Aspiration not often evident in this London region? (4,3)

I believe the answer is:
east end
'aspiration not often evident in this' is the definition.
The definition suggests a singular noun which matches the answer.
'london region?' is the wordplay.
'london' becomes 'east' (I can't explain this - if you can you should believe this answer much more).
'region?' becomes 'end' (end is a kind of region).
'east'+'end'='EAST END'
Can you help me to learn more?
(Other definitions for east end that I've seen before include "Side of London associated with Cockneys (4.3)" , "Tower Hamlets area" , "part of the capital" , "ockney London" , "where plates are for standing on?" .)
