Grassland in Little Avon (3)
I believe the answer is:
lea
'grassland' is the definition.
(lea is a kind of grassland)
'in little avon' is the wordplay.
'in' indicates a hidden word.
'LEA' is hidden in the letters of 'little avon'.
(Other definitions for lea that I've seen before include "Open pasture" , "grazing area" , "Open grassy land; river" , "Grass area" , "Open arable land (poet.)" .)