Idiom About the Inevitable, "walk the __"

This page is the CodyCross answer for the clue below from Sense of Smell, Group 1470, Puzzle 2 (Christmas Trees).

Question is: Idiom About the Inevitable, "walk the __"

and the answer is: GREENMILE

Word Meaning:

GREEN — The color of grass and leaves; a primary additive color midway between yellow and blue which is evoked by light between roughly 495–570 nm.

Definitions from Wiktionary.