Grazing expanse (3)
I believe the answer is:
lea
'grazing expanse' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lea that I've seen before include "Poetically, a piece of meadow or pasture" , "'The lowing herd wind slowly o'er the . . .'" , "Land growing grass" , "Open grassy land; river" , "Grass area" .)