Area of grassland (5)
'area of grassland' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for meadow that I've seen before include "area of grassland" , "In rural location" , "Area used for hay" , "Low ground near river" , "Tract of cultivated grassland" .)
(Other definitions for field that I've seen before include "Deal with" , "Piece of grassland" , "See 20" , "Area of farm land" , "Area for crops" .)