The most common and most likely answer to this crossword clue is the 11 letter word REGATHERING
I've seen this crossword clue in The Times
R
E
G
A
T
H
E
R
I
N
G
Buddy explains!
The straight part
We know that "getting back together again" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case getting back together again = regathering.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 REGATHERING mean?
REGATHERING verb- Gather again, gather back together