The most common and most likely answer to this crossword clue is the 6 letter word COSMIC
I've seen this crossword clue in The Daily Telegraph
C
O
S
M
I
C
More clues leading to the result COSMIC
- Funny guy collects Sierra from space
- Universal wit entertaining third of listeners
- Publication about someone originally from space
- Universal start of sale promotion for Marvel productions?
- Because I’m travelling skywards, the speed of light is enormous
- Huge, funny man disguises the end of punchlines
- Significant comedian around the South
- Very important reading matter for children engrosses son
- Huge kids’ publication — son is absorbed
- Huge company thus pockets millions
Buddy explains!

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.
What does COSMIC mean?
COSMIC adjective- Of or from or pertaining to the cosmos or universe.
- Characteristic of the cosmos or universe; inconceivably great; vast.
- Rising or setting with the sun; not acronycal.