* Celebrities' personal lives are private: Actors don't always share every detail of their lives.
* Rumors are unreliable: Unless Leo Howard himself confirmed it, any information about his fear of clowns is likely speculation.
If you're curious about Leo Howard, you could try looking for interviews where he might have discussed his fears, or look for social media posts where he might have expressed something related to this. However, remember that even then, it's not a guarantee of accurate information.