The most common and most likely answer to this crossword clue is the 9 letter word INTROVERT
I've seen this crossword clue in Financial Times
I
N
T
R
O
V
E
R
T
More clues leading to the result INTROVERT
- A shy person, traveller stops during races
- Popular races engaging traveller, one not boosted by others
- . Solitary man rising and following in time
- Sort of personality: international Mars explorer has tons
- TV writer on leaving wife becomes withdrawn
- Withdrawn? Still, there’s much treasure to be found within
- Mouse in races overcoming dog
- Vagrant entered in race is withdrawn
- Dog’s entered in races as one withdrawn
- Shy person beginning to get, for the most part, really tense
Buddy explains!

The straight part
We know that "withdrawn" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case withdrawn = introvert.The cryptic/wordplay part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.