I cannot work out 6d. It's part of a clue whose full answer, I believe is a short phrase "?a?e Gooseberry". The clue for 6,16,28 is:
Cover unwanted third with...(4,10)
I ended up with the letters: ?a?e g?o?e b?r?y
The other one is 25d
Turtle in the mystery plays (4) E?y? is it emys, or eryp? I cannot find either.
Explanations warmly welcomed.