The most common and most likely answer to this crossword clue is the 9 letter word ASTRONAUT
I've seen this crossword clue in Financial Times
A
S
T
R
O
N
A
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T
More clues leading to the result ASTRONAUT
- Job in space needs a mostly robust adult regularly employed
- One travelling to Saturn?
- Foremost of adventurers travelling to Saturn?
- One to depart this world like man strapped in tight?
- A confident walk catching on with a spaceman
- So a truant morphed into a high-flier?
- Adult blasting to Saturn?
- Space traveller’s American out to Saturn
- Space traveller advanced to Saturn in error
- Motion of Saturn to a space traveller
Buddy explains!

The straight part
We know that "Adult blasting to Saturn" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case adult blasting to saturn = astronaut.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 ASTRONAUT mean?
ASTRONAUT noun- A member of the crew of a spaceship or other spacecraft that travels beyond Earth's atmosphere, or someone trained to serve that purpose.
- A returnee who frequently flies back and forth between Hong Kong and his/her adopted home country.