Not all leaves are green (3)
I believe the answer is:
lea
'green' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'not all leaves are' is the wordplay.
'not all leaves' becomes 'le' (I can't explain this - if you can you should give a lot more credence to this answer).
'are' becomes 'a' (short for 'are', historical unit of measurement).
'le'+'a'='LEA'
Can you help me to learn more?
(Other definitions for lea that I've seen before include "Open area of grassy or arable land" , "Poetically, a piece of meadow or pasture" , "''The lowing herd winds slowly o'er the ... '' (Gray)" , "pastoral setting" , "Open arable land (poet.)" .)