Hopkins tells is he had lightening in mind when he wrote this line. If you shake an ordinary piece of tinfoil, you can see what he may have envisioned. We see a flash of fire, but only a flash. The lines addresses things, which are beautiful, but temporary.
[…]ooze of oil […] Crushed. (3-4)
The alliterations here sound rich and luxurious, like a massage. Perfume is made from oil. A variety of substances are "crushed" to release their fragrance as oil. Oil is also used in religious ceremonies. Yet, if we take too much oil, we have environmental problem, leaving the earth crushed.
And all is seared with trade; bleared, smeared with toil; (6)
The poet only describes the surface of the world as being polluted. If something is charred, it’s burned all the way through to the core. If something is seared, only the surface is burned. That something is seared, is painful but not fatal. Also in this quotation we see the word, "bleared." Bleared is similar to "blurred." It’s how something looks, not how it is. Again, Hopkins seems to be making the claim that If we stop abusing the earth, the smears will go away.
And for all this, nature is never spent. (9)
Spent is an interesting word choice. It makes us think of "trade" and money. The line means nature can’t run out, but also perhaps that it can’t be bought – no amount of money can completely destroy it. It is this line that gives us a glimmer of hope about the state of the natural world.
[…]dearest freshness deep down things […] (10)
Yep, as we said, the damage is only on the surface of things, underneath all is fresh and sweet, but buried and hidden away.
[…] last lights off the black West went (11)
This is a fancy way of saying that the sun set in the west, and then the sky become dark. To the speaker of this poem, this natural phenomenon is no small miracle. The "morning" that follows it is an even bigger miracle. In spite of all the doom and gloom of life, the light just keeps on following the darkness. This could serve as a metaphor for human treatment of the earth. After a period of darkness and damage, there can still be lightness and healing.