"Ella tiene una idea."
Traducción:She has an idea.
In english we don't really interchange clue and idea, except for the situation where a person doesn't know something...
What happened here? I have no idea.
What happened here? I have no clue.
Both are acceptable in that situation, but the rest of the time you should keep them separate (idea y clave)
"I had a good idea that solved the problem" but not "I had a good clue that solved the problem".
"The detective found a clue that eventually solved the crime", but not "The detective found an idea that eventually solved the crime"