Probably the quickest solution to this (if it’s urgent) would be to spin up a linux virtual machine and run one of the supported packages. If this were a one time need, it’s likely what I’d do myself.
I took a quick look at https://community.kde.org/Kdenlive/Development/KF5. The package has a lot of dependencies. It’s going to be a non-trivial amount of work to get this over the line for homebrew. If you’re unfamiliar with compiling packages, this is going to be hard, but the reward of learning might make it worth your while.
If you want to do the compilation, the link above would be your staring point. You’d want to identify which of the referenced libraries are already in homebrew and which would need to be added. Particularly note the list of dependencies to install if you’re compiling on linux. The names in homebrew for those libraries may be similar, but will often drop version numbers,
lib prefixes, and
-dev suffixes etc.