The most common and most likely answer to this crossword clue is the 4 plus 9 letter word SNOW BLINDNESS
I've seen this crossword clue in The Daily Telegraph
S
N
O
W
B
L
I
N
D
N
E
S
S
More clues leading to the result SNOW BLINDNESS
Buddy explains!
The straight part
We know that "Lack of sense caused by a fall" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lack of sense caused by a fall = snow blindness.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.