The most common and most likely answer to this crossword clue is the 11 letter word ECOFRIENDLY
I've seen this crossword clue in The Daily Telegraph
E
C
O
F
R
I
E
N
D
L
Y
More clues leading to the result ECOFRIENDLY
Buddy explains!

The straight part
We know that "Green" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case green = ecofriendly.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ECOFRIENDLY mean?
ECOFRIENDLY adjective- Ecologically friendly; not damaging to the natural environment.