The most common and most likely answer to this crossword clue is the 15 letter word JACK-IN-THE-BOX
I've seen this crossword clue in Financial Times
J
A
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More clues leading to the result JACK-IN-THE-BOX
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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 JACK-IN-THE-BOX mean?
JACK-IN-THE-BOX noun- Children’s toy where a figure pops out of a small box.
- A con-man who deceived tradesmen by substituting empty boxes for others full of money.