Grassy surface (3)
I believe the answer is:
sod
'grassy surface' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sod that I've seen before include "Lump of earth" , "Piece of peat or grass" , "Surface layer of ground with grass roots" , "'Sward, turf (3)'" , "A lulmp of turf" .)