We had got the gun in central London (4,3)
'central london' is the definition.
The definition and answer can be both locations as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'we had got the gun' is the wordplay.
'had' becomes 'd' (I've seen this in other clues).
'got' indicates putting letters inside.
'the gun' becomes 'sten' (British sub-machine gun).
'wed' enclosing 'sten' is 'WEST END'.
'in' is the link.
Can you help me to learn more?
(Other definitions for west end that I've seen before include "lots of entertainment here", "Part of central London", "London theatre district", "London theatre area", "Fashionable part of London".)