Fun! I think "Lightens" should be "Lighten" to match the tense of the answer, and 4D might be improved by more clearly indicating that ET comes after IB ("alien passes education program"?). Otherwise really enjoying your foray into cryptics!
Nice clues, fun enough to solve. Education program is something in UK (I'm in US, don't know that reference)?
Next level on cluing is to have the clues themselves have improved meaning, i.e., more clues like 1!