There’s probably gonna be a few confusions from AL’s comments, so here’s where you have them solved.
18 down: Yarn to floor in America (5)(8 after theme applied)
I’m betting I don’t know the word.
8 across: Pothead confronts delicate problem (6)
If the answer does indeed go pothead confronts delicate = p confronts light = plight = problem, aren’t plight = problem and delicate = light highly questionable synonyms?