The most common and most likely answer to this crossword clue is the 10 letter word PREHISTORY
I've seen this crossword clue in The Daily Telegraph
P
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More clues leading to the result PREHISTORY
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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 PREHISTORY mean?
PREHISTORY noun- (properly) History before written records, inclusive of both
- Any past time (even recent) treated as such a distant, unknowable era.
- (often as pre-history) The history leading up to some event, condition, etc.