The most common and most likely answer to this crossword clue is the 9 letter word NON-EVENT
I've seen this crossword clue in The Guardian
N
O
N
-
E
V
E
N
T
More clues leading to the result NON-EVENT
Buddy explains!
The straight part
We know that "anticlimax" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case anticlimax = non-event.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 NON-EVENT mean?
NON-EVENT noun- A situation which, contrary to expectation, turned out to be uninteresting, unimportant or unexciting; an anticlimax.
- A publicised event which does not take place.