The most common and most likely answer to this crossword clue is the 8 letter word JAMBOREE
I've seen this crossword clue in The Times
J
A
M
B
O
R
E
E
More clues leading to the result JAMBOREE
- Dull WI member perhaps joining English party
- Crowd wave before English party
- Setter weary before end of house party
- Crowd carried east for large rally
- Gathering pace finally, force trial to go ahead
- Sticky situation tolerated by first of expats in lively gathering
- Scouts do stick first of badges on right sleeve in the middle
- Crowd supported end to fine, lively celebration
- Press irritate Oriental in rally
- Conserve energy after tedious person’s party
Buddy explains!

The straight part
We know that "Gathering" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gathering = jamboree.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 JAMBOREE mean?
JAMBOREE noun- A boisterous or lavish celebration or party.
- A frolic or spree.
- A large rally of Scouts or Guides.
- In euchre: an undefeatable hand containing the five highest cards.