The northernmost borough of London (7)
I believe the answer is:
enfield
'the northernmost borough of london' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for enfield that I've seen before include "London suburb" , "Feel din of Kildare town" , "Big centre" , "NE London borough" , "North London borough" .)