The most common and most likely answer to this crossword clue is the 10 letter word GATHERINGS
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result GATHERINGS
Buddy explains!

The straight part
We know that "parties" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case parties = gatherings.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 GATHERINGS mean?
GATHERINGS noun- A meeting or get-together; a party or social function.
- A group of people or things.
- A section, a group of bifolios, or sheets of paper, stacked together and folded in half.
- A charitable contribution; a collection.
- A tumor or boil suppurated or maturated; an abscess.