The most common and most likely answer to this crossword clue is the 11 letter word MUMBO-JUMBO
I've seen this crossword clue in The Guardian
M
U
M
B
O
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J
U
M
B
O
More clues leading to the result MUMBO-JUMBO
Buddy explains!
The straight part
We know that "incomprehensible" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case incomprehensible = mumbo-jumbo.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 MUMBO-JUMBO mean?
MUMBO-JUMBO noun- A deity or other supernatural being said to have been worshipped by certain West African peoples; an idol.
- Any object of superstition; religious words and/or actions which are seen as superstitious or fraudulent.
- (by extension) Any confusing or meaningless speech; nonsense, gibberish.