The most common and most likely answer to this crossword clue is the 8 letter word DOWNWARD
I've seen this crossword clue in The Times
D
O
W
N
W
A
R
D
More clues leading to the result DOWNWARD
Buddy explains!

The straight part
We know that "Falling" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case falling = downward.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 DOWNWARD mean?
DOWNWARD adjective- Moving, sloping or oriented downward.
- Located at a lower level.
- Toward a lower level, whether in physical space, in a hierarchy, or in amount or value.
- At a lower level.
- Southward