The most common and most likely answer to this crossword clue is the 10 letter word STIPULATED
I've seen this crossword clue in The Guardian
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More clues leading to the result STIPULATED
Buddy explains!

The straight part
We know that "Specified" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case specified = stipulated.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 STIPULATED mean?
STIPULATED verb- To require (something) as a condition of a contract or agreement.
- To specify, promise or guarantee something in an agreement.
- To acknowledge the truth of; not to challenge. E.g. "The defense stipulates that the witness has identified my client."
- Required as a condition of a contract or agreement.
- Specified, promised or guaranteed in an agreement.