Grazing in an arable area (3)
I believe the answer is:
lea
'grazing' is the definition.
(thesaurus)
'in an arable area' is the wordplay.
'in' 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 "Open pasture" , "Pasture, London river" , "River of east London" , "Grazing land" , "Poetically, a piece of meadow or pasture" .)