We had got the gun in central London (4,3)
I believe the answer is:
west end
'central london' is the definition.
The definition and answer can be both locations as well as being singular nouns.
Maybe there's a link between them I don't understand?
'we had got the gun in' is the wordplay.
'had' becomes 'd' (in contractions e.g. 'I'd', 'you'd' etc).
'got' is a charade indicator (letters next to each other).
'the gun' becomes 'sten' (British sub-machine gun).
'in' is an insertion indicator.
'we'+'d'='wed'
'wed' going around 'sten' is 'WEST END'.
Can you help me to learn more?
(Other definitions for west end that I've seen before include "Fashionable part of London" , "London theatre district" , "London's theatreland" , "London theatre area" , "Part of central London" .)