The most common and most likely answer to this crossword clue is the 6 plus 6 letter word SENIOR MOMENT
I've seen this crossword clue in The Daily Telegraph
S
E
N
I
O
R
M
O
M
E
N
T
More clues leading to the result SENIOR MOMENT
Buddy explains!

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.