The most common and most likely answer to this crossword clue is the 9 letter word CONCERNED
C
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Buddy explains!

The straight part
We know that "Worried about" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case worried about = concerned.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 CONCERNED mean?
CONCERNED verb- To relate or belong to; to have reference to or connection with; to affect the interest of; to be of importance to.
- To engage by feeling or sentiment; to interest.
- To make somebody worried.
- Showing concern.
- Involved or responsible.