Then leaf subsides to leaf. (5)
It turns out our speaker prefers the early leaves to the later ones; otherwise, he probably wouldn't have used the term "subsides."
So Eden sank to grief, (6)
Perhaps the most fantasized-about natural world in existence is the biblical Garden of Eden. There, things were perfect, beautiful, and serene. There was always enough to eat, and the first humans, Adam and Eve, had no worries. But, just like blooms turn into leaves and gold turns to green, when Eve sinned by eating from a forbidden tree, Eden came to grief. Bummer, dude.
So dawn goes down to day. (7)
We've jumped from the fantastic Garden of Eden to an everyday occurrence: the change from dawn to day. Again, we see how the beauty of dawn and its brilliant colors are only temporary and give way all too soon to daylight.