The most common and most likely answer to this crossword clue is the 4 plus 5 letter word DEEP SPACE
I've seen this crossword clue in The Sunday Telegraph
D
E
E
P
S
P
A
C
E
More clues leading to the result DEEP SPACE
- Energy to limit velocity when rocketing in void
- Return of expedition, walk somewhere far, far away
- Pace back and forth to find where the stars are
- Hurry back, then walk somewhere far off
- Over the moon here to have secret room
- Went back to room that’s out of this world
- Better hurry back to Earth as it’s a long way off
- Limit velocity returning to Earth from out here
- Ebbing and flowing tempo that’s out of this world!
- Velocity rising with single step in void
Buddy explains!
The straight part
We know that "that’s out of this world!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that’s out of this world! = deep space.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.