Districts around northern stadia (6)
I believe the answer is:
arenas
'stadia' is the definition.
('arena' can be a synonym of 'stadium')
'districts around northern' is the wordplay.
I cannot really understand how this works, but
'northern' could be 'n' (abbreviation e.g. N. Ireland) and 'n' is present in the answer.
'districts' could be 'areas' (I've seen this in another clue) and 'areas' is found in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for arenas that I've seen before include "Areas of endeavours" , "Areas for events, sports perhaps" , "Central areas of, say, sports stadiums" , "Sports venues" , "Level areas in centre of sports stadiums" .)