The most common and most likely answer to this crossword clue is the 9 letter word HAPPENING
I've seen this crossword clue in The Daily Telegraph
H
A
P
P
E
N
I
N
G
Buddy explains!

The straight part
We know that "Experience" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case experience = happening.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 HAPPENING mean?
HAPPENING verb- To occur or take place.
- To happen to; to befall.
- (with infinitive) To do or occur by chance or unexpectedly.
- (followed by on or upon) To encounter by chance.
- (of a place) Busy, lively; vibrant, dynamic; fashionable.
- (of a person or product) Trendy, up-to-the-minute.
- Something that happens.
- A spontaneous or improvised event, especially one that involves audience participation.