The most common and most likely answer to this crossword clue is the 7 letter word MUMMERY
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Buddy explains!
The straight part
We know that "pretentious ceremony" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pretentious ceremony = mummery.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 MUMMERY mean?
MUMMERY noun- Mumming; disguising oneself to perform as a mummer, or to take part in some other festivities or performance.
- A ridiculous or ostentatious ceremony, formerly especially of a religious nature; extravagant or hypocritical performance.