The most common and most likely answer to this crossword clue is the 8 plus 4 letter word ASTEROID BELT
I've seen this crossword clue in Financial Times
A
S
T
E
R
O
I
D
B
E
L
T
More clues leading to the result ASTEROID BELT
- 50 per cent of satellites orbited off course in region of solar system
- A drug ring supplying interplanetary travellers
- Amateur band bags drug for rock group
- A couple of items boxer may have, circling ring?
- A drug district — space that's largely stoned
- One means of improving athletic performance: live with military officer somewhere beyond Mars!
Buddy explains!
The straight part
We know that "circling ring" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case circling ring = asteroid belt.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.