The most common and most likely answer to this crossword clue is the 8 letter word NOSEDIVE
I've seen this crossword clue in Financial Times
N
O
S
E
D
I
V
E
More clues leading to the result NOSEDIVE
- Talent for finding underground bar for a quick drop
- Void seen after dizzying plunge
- Headlong fall? Nothing to ease the pain at cut
- Reportedly understands seedy bar’s sharp decline
- Hooter goes before dodgy club go into decline
- Steep decline in doves flying close to shore
- Take the plunge suddenly? No, I have to get around Home Counties date initially
- See on vid horrific headlong plunge
- Made enquiries on one case of vehicle’s sudden fall
- Adam’s female relative over around day one’s Fall
Buddy explains!

The straight part
We know that "sharp decline" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sharp decline = nosedive.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 NOSEDIVE mean?
NOSEDIVE noun- A headfirst fall or jump.
- A rapid fall in price or value.
- (of aircraft) To dive down in a steep angle.
- To perform a rapid fall in price or value.