?
Why not?
If you have room (ex. you don’t fill up the allotted space with activities that are more important to you) then it is perfectly fine to list it. Does the speech camp relate to any activities you do?
My kid did. Actually, she made “Speech” an activity, said “See Additional Info” in the description, then had a header for Speech in the A’ddl Info section and bulleted our things like speech camp underneath.