8a. "Aurally prosecute Native American" (5) sorry no letters, however 4d second letter is 8a second letter of which the clue is "Fossil observed outside underground chamber" (4) ? ? ? O. Plus 8a fourth letter is 5d second letter of which the clue is "Where in France release mechanism is on spar" (9) ? ? ? R G ? ? ?.
Well if you're not confused I am!
16a. "Like-minded sort, embarrassed" (7) ? I ? D ? ? ?