The most common and most likely answer to this crossword clue is the 5 plus 5 letter word OZONE LAYER
I've seen this crossword clue in The Times
O
Z
O
N
E
L
A
Y
E
R
More clues leading to the result OZONE LAYER
- Visiting Australia the queen, I bet, gets high-level protection
- Old region developed early. It’s above the earth
- Down under a hen, possibly to get protection from the sun
- Harmful rays absorbed here nearly ooze out
- Sunblock that’s nearly ooze when spread
- Protection for us from Australia – a hen!
- Only place for a film “It’s up in the sky”
Buddy explains!
The straight part
We know that "high-level protection" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case high-level protection = ozone layer.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.