Some green, fertile area (3)
I believe the answer is:
lea
'some green fertile area' is the definition.
'lea' can be an answer for 'area' (lea is a kind of area). I am not sure about the 'some green fertile' bit.
'some green fertile area' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'LEA' is hidden in the letters of 'green fertile area'.
Can you help me to learn more?
(Other definitions for lea that I've seen before include "authority for teachers" , "Land growing grass" , "Grazing land" , "River flowing through London" , "Open arable land (poet.)" .)