The most common and most likely answer to this crossword clue is the 9 letter word COHOSTING
I've seen this crossword clue in The Times
C
O
H
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More clues leading to the result COHOSTING
Buddy explains!
The straight part
We know that "Helping with party" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case helping with party = cohosting.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 COHOSTING mean?
COHOSTING verb- To act as a joint host.
- To store data or applications on a shared server (as in web hosting).