Has anybody written/found a guide along the lines of "writing clojure in spacemacs" ? I feel like there's probably a lot of stuff I'm not doing, or stuff I've misconfigured.

I think @jr0cket has done some excellent work on that, there's definitely a youtube video and blogposts

There is a partially done github hosted ebook by @jr0cket which gives excellent pointers and hints.

https://github.com/practicalli/spacemacs-gitbook