I saw the following bit in the emacs-devel archives:

some files may consist of several parts requiring different tree-sitter
grammars. For example, a JavaScript file may have its documentation
written with jsdoc: JavaScript and jsdoc have a tree-sitter grammar
each.

Is there a way to use a tree-sitter grammar in parts of the file and
another one in other parts? There could be a main grammar and secondary
grammars would be activated on some kinds of nodes of the main one.

Yes, it should be possible, AFAIU. See the node "Multiple Languages"
in the ELisp manual, I believe it explains how to do what you want.

As an idea for "somewhere down the line", perhaps it would be interesting to consider the following...

Since tree-sitter-clojure can recognize regex literals, may be one could apply an appropriate regular expression grammar to highlight the portions within the double quotes.

I don't know how close this grammar is to Clojure's flavor of regex, but may be it or some appropriate modification to it (or something that inherits from it) might be used for the task.

For reference, the part of the manual being referred to in the quote above can be see in .texi form here. I didn't manage to find an HTML version. If you've got a recent enough Emacs from the emacs-29 branch, the info may be viewable from within emacs. Worked for me anyway...

Ah sorry. May be I should have made this in the Discussions area?