Green LIGHT (permission to start) and green THUMB (talent for growing plants) are figures of speech.
Beyond that, a number of things could be green, but a green YARD (lawn) is desirable?
After reading spoilers: Missed TRAIN, a green (eco-friendly) mode of transport.
I would guess LIGHT > THUMB > TRAIN > YARD.
Could swap YARD with something else.
Other words with possible connections: Track, Fall, Light, Nut, Carrot, Mexico, Scale, Australia. Of those, I like Nut and Scale best, would happily sub either in for Band.
Green LIGHT is an expression, right?
Green THUMBs are good at gardening.
European DRAGONs are often green, I think.
MEXICO has green on the flag?
YARDs can be green, with a lawn?
I feel pretty good about the first three, not sure about the 4 and 5.
After spoilers, I think I like yard better than mexico, although I don't hate either. Green could be a reasonable way to clue Mexico without clueing Australia, maybe?
