Go fuck yourself with your atom bomb (5)
Okay! Well, that was… ahem, direct! Clearly, though, the speaker's got some very passionate feelings about America's use of nuclear weapons. It's just one of his many gripes with the country, really. And, with this poem coming less than a decade after the bombing of Hiroshima and Nagasaki, we imagine his political opinions are given energy by his recent memory.
When will you be worthy of your million Trotskyites? (11)
If you don't already know, Leon Trotsky was a Russian political theorist and revolutionary, as well as a champion of communism and workers' rights. Here the speaker is planting his flag firmly in the communist camp, telling capitalist America (which was in the middle of the Cold War with the communist Soviet Union) that it's not fit even to house one million of Trotsky's sympathizers.
America I feel sentimental about the Wobblies. (27)
This nickname always makes us giggle. Sure, "member of the Industrial Workers of the World union" doesn't really roll off the tongue, but, come on. Wobblies? Their name is not what matters to the speaker, though. What he misses about them are the politics that the Wobblies were associated with: pro-worker, pro-labor, and pro-union. The speaker is down for their political cause, and he's not wobbling on his position.