Call for perspectives on a passage

I have been working on a woodwind trio for which I have written a passage which has been confusing at best. As I tend to be guided by my ear when writing, I sometimes write things that sound aligned with my expectations but which I do not entirely understand! This seems to be amplified when I use chromaticism, as in this example. 

I think I now understand, but I am a bit stuck on what to write in the inner voice. 

My understanding is that the first two bars mark the dominant of A minor, with a D sharp chromatic inflection in the bass in the second but which resolves in the third beat. And the third bar is I in A minor, with a C sharp chromatic inflection implying d minor but resolving to an A minor chord. This proceeds to the V7 of A minor in preparation for the cadence in Am (but in fact resolves to F major). 

The upper voice descends chromatically in such a way that complicates the harmony and opportunities to fill in the middle voice. My low experience with chromaticism really shows its true colors here. 

I have attached the audio - the passage in question is from the 50 second mark. 

Would be great to hear other's perspectives. 

Hey Markus, I haven't seen you in a while, glad to hear you're still writing 🙂 

I love these kinds of posts. It's really cool to hear your problem, then for me to try it out and mess around on it. Thanks for posting your thought process, as I can start with yours and see where that takes me. 

One idea I had was to let the clarinet be a pedal point for the E7. I had F for the "Dm" chord measure, but it didn't sound good to me. I liked the absence of the clarinet here, so maybe keep it simple if this thought leads you somewhere. 

For me, it helps to see the entire 4 bar phrase as E7. I know that one spot is tricky, but it just seems like a big cadence to Am (Also, this whole transition from Bb to F is wonderful and very smooth. Is it Am - C7 - F? I like the iii - V7 - I movement). If I look at it as E7 with a bunch of chromatics, it's easier to think about the clarinet. I came up with this pretty quick, I'm sure the notes could be tinkered with. I don't remember, but little rhythmic motifs you may have used could go well with the clarinet, I just came up with something simple. 

Oh, and our music player sucks lol. It's hard to go to a certain spot within a piece, so I think I've heard the first minute or so several times 😄 

Hopefully some of these thoughts are useful 🙂 

Great stuff, keep us updated!

P.S. The bassoon starts on B nat. right?