Meadow within arable area (3)
I believe the answer is:
lea
'meadow' is the definition.
(a lea is a grassy area)
'within arable area' is the wordplay.
'within' says the answer is hidden in the clue.
'LEA' can be found hidden inside 'arable area'.
(Other definitions for lea that I've seen before include "Pasture, London river" , "Open pasture" , "Tract of pastureland" , "grazing area" , "Poetically, a piece of meadow or pasture" .)