The most common and most likely answer to this crossword clue is the 10 letter word TO-AND-FRO
I've seen this crossword clue in The Times
T
O
-
A
N
D
-
F
R
O
Buddy explains!
The straight part
We know that "as Shuttle moves" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case as shuttle moves = to-and-fro.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 TO-AND-FRO mean?
TO-AND-FRO noun- The movement (of someone or something) forward followed by a return to the same position. May refer to a concept such as an emotional state or a relationship as well as a physical thing.
- To go back and forth; to alternate.
- Pertaining to something or someone moving forward and back to the same position.