Grassland in Steeple Aston (3)
I believe the answer is:
lea
'grassland' is the definition.
(lea is a kind of grassland)
'in steeple aston' is the wordplay.
'in' says the answer is hidden in the clue.
'LEA' can be found hidden inside 'steeple aston'.
(Other definitions for lea that I've seen before include "River flowing through London" , "Open area of grassy or arable land" , "Poetically, a piece of meadow or pasture" , "area of grassland" , "grazing area" .)