Sphere of conflict is region round the north (5)
I believe the answer is:
arena
'sphere of conflict' is the definition.
(I've seen this in another clue)
'region round the north' is the wordplay.
'region' becomes 'area' (synonyms).
'round' indicates putting letters inside.
'the north' becomes 'N' (abbreviation).
'area' enclosing 'n' is 'ARENA'.
'is' is the link.
(Other definitions for arena that I've seen before include "Sporting enclosure" , "Field of battle" , "Gladiatorial ring" , "Space for public events" , "park" .)