The most common and most likely answer to this crossword clue is the 10 letter word POSTMORTEM
I've seen this crossword clue in The Guardian
P
O
S
T
M
O
R
T
E
M
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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 POSTMORTEM mean?
POSTMORTEM noun- An investigation of a corpse to determine the cause of death.
- Any investigation after the conclusion of an activity, particularly when said activity produces an unwanted outcome.