Green cornfield after ploughing you turned up to take in (3-8)
I believe the answer is:
'green' is the definition.
(I know that green can be written as eco-friendly)
'cornfield after ploughing you turned up to take in' is the wordplay.
'after ploughing' indicates anagramming the letters (letters ploughed or worked over).
'you' becomes 'ye' (historical version of 'you').
'turned up' says the letters should be written backwards.
'to take in' is an insertion indicator.
'ye' back-to-front is 'ey'.
'cornfield' with letters rearranged gives 'cofriendl'.
'cofriendl' placed within 'ey' is 'ECO-FRIENDLY'.
(Other definitions for eco-friendly that I've seen before include "Not harmful to the environment" , "In harmony with the environment" .)