The most common and most likely answer to this crossword clue is the 8 letter word BUNFIGHT
I've seen this crossword clue in Financial Times
B
U
N
F
I
G
H
T
Buddy explains!

The straight part
We know that "Party" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case party = bunfight.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 BUNFIGHT mean?
BUNFIGHT noun- A debate or disagreement, usually with several parties involved, often political in nature.
- A formal tea party or other social gathering, especially one at which food is served.