Going down, lands in northern city (10)
I believe the answer is:
sunderland
I believe this is a double definition.
'going down lands' is the first definition.
(in a down clue, 'lands' is S 'under' LAND)
'northern city' is the second definition.
(city in the north east of England)
'in' acts as a link.
(Other definitions for sunderland that I've seen before include "Footballers" , "City on the River Wear" , "City of NE England" , "City near 17[STOCKTON]" , "Port near Newcastle" .)