The most common and most likely answer to this crossword clue is the 9 letter word GERONIMO!
I've seen this crossword clue in Financial Times
G
E
R
O
N
I
M
O
!
Buddy explains!
The straight part
We know that "Here goes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case here goes = geronimo!.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 GERONIMO! mean?
GERONIMO! interjection- A cry before jumping out of or into something (originally by American parachutists).