In London, a nurse's station? (5)
I believe the answer is:
angel
'in london' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'a nurse's station?' is the wordplay.
'a' becomes 'an'.
'nurse's station?' becomes 'gel' (I can't explain this - if you can you should believe this answer much more).
'an'+'gel'='ANGEL'
Can you help me to learn more?
(Other definitions for angel that I've seen before include "Divine messenger" , "Person of beauty, purity or kindness?" , "Glean (anag.)" , "Cloud resident?" , "Messenger < is a nurse" .)