The most common and most likely answer to this crossword clue is the 10 letter word CLASSIFIED
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result CLASSIFIED
- Secret group I dismissed, right away
- Pupils I gave dinner to around one in secret
- Like some ads to be withheld for security
- As CID files, possibly
- Graded fiscal side ‘uncertain’
- Confidential Catholic girl provided current education
- CIA’s files reviewed and ultimately marked confidential
- Sorted secret type of advertisement?
- Secret identity masking expression of disgust by Catholic female
- When improvised explosive device is planted after school session, it is secret information
Buddy explains!

The straight part
We know that "Sorted/secret/type of advertisement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sorted/secret/type of advertisement = classified.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 CLASSIFIED mean?
CLASSIFIED adjective- Sorted into classes or categories
- Formally assigned by a government to one of several levels of sensitivity, usually (in English) top secret, secret, confidential, and, in some countries, restricted; thereby making disclosure to unauthorized persons illegal.
- Not meant to be disclosed by a person or organization.
- To identify by or divide into classes; to categorize
- To declare something a secret, especially a government secret
- A classified advertisement in a newspaper or magazine.