Specifically what you want is to provably halt and to be free of side effects. There's some configuration languages with these properties for providing expressions in JSON configs (I'm blanking on their names for the moment) which generally don't advertise themselves as Lisp dialects but boil down to a Lisp AST written in JSON. Another example is Starlark, which provides Python-like syntax.

Note that this implies a Turing incomplete language. Which makes sense - our goal is to make dangerous programs unrepresentable, so naturally we can't implement every algorithm in our restricted language.