The most common and most likely answer to this crossword clue is the 9 letter word EVENTUATE
E
V
E
N
T
U
A
T
E
More clues leading to the result EVENTUATE
- Turn out upper-class in gallery after literary evening
- Love in progress to make things happen slower in song
- Turn out flat, stretched over back of frame
- Work out, held back by muscle, taut nevertheless
- Happen to be in flat by gallery outside university
- Turn out in uniform, classy, to appear in gallery
- Still tense about election’s initial turn out
Buddy explains!

The straight part
We know that "happen / song" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case happen / song = eventuate.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 EVENTUATE mean?
EVENTUATE verb- To have a given result; to turn out (well, badly etc.); to result in.
- To happen as a result; to come about.