The most common and most likely answer to this crossword clue is the 12 letter word PORTMANTEAUS
I've seen this crossword clue in Financial Times
P
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T
M
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Buddy explains!
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 PORTMANTEAUS mean?
PORTMANTEAUS noun- A large travelling case usually made of leather, and opening into two equal sections.
- A schoolbag.
- A hook on which to hang clothing.
- A portmanteau word.