Sod (4)
I believe the answer is:
turf
'sod' is the definition.
(I know that sod can be written as turf)
This is all the clue.
(Other definitions for turf that I've seen before include "This accountant is a bookie" , "Grass clod" , "Surface layer of ground matted with grass" , "Grass; (one's) territory" , "Laid grass" .)