The most common and most likely answer to this crossword clue is the 8 letter word POCKETED
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Buddy explains!

The straight part
We know that "concealed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case concealed = pocketed.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 POCKETED mean?
POCKETED verb- To put (something) into a pocket.
- To cause a ball to go into one of the pockets of the table; to complete a shot.
- To take and keep (something, especially money that is not one's own).
- To shoplift; to steal.
- To put up with; to bear without complaint.