The most common and most likely answer to this crossword clue is the 9 letter word NIGHTFALL
I've seen this crossword clue in The Guardian
N
I
G
H
T
F
A
L
L
More clues leading to the result NIGHTFALL
- What to say at bedtime about following evening
- Man decapitated before autumn, when it gets dark
- Mixed half a G&T in and left for end of the day
- Strange thing left by river just after sunset?
- Unusual thing occurring prior to Maine’s autumn sunset
- Nearly time to crash?
- Day trip? Quite the contrary
- Collapse under thing roaming in gloaming
- evening
- When evening begins, declared champion goes over defeat
Buddy explains!

The straight part
We know that "Nearly time to crash" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nearly time to crash = nightfall.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 NIGHTFALL mean?
NIGHTFALL noun- The close of the day; the coming of night.