Subdivision; quarter (6)
I believe the answer is:
sector
I believe this clue is a double definition.
'subdivision' is the first definition.
(I have seen 'Subdivision of area ' mean 'sector' so perhaps 'subdivision' could also mean 'sector')
'quarter' is the second definition.
(I've seen this before)
(Other definitions for sector that I've seen before include "Area of circle between two radii" , "Area, division" , "Part of a pie chart" , "battle zone" , "Area covered by corset" .)