Race round some land (4)
I believe the answer is:
acre
'some land' is the definition.
(unit of land)
'race round' is the wordplay.
'round' indicates anagramming the letters.
'race' anagrammed gives 'ACRE'.
(Other definitions for acre that I've seen before include "stretch of land" , "Four roods - Israeli port" , "point four nought five of a hectare" , "Care about the piece of land" , "region of ground" .)