The most common and most likely answer to this crossword clue is the 6 plus 5 letter word DOUBLE DUTCH
I've seen this crossword clue in The Daily Telegraph
D
O
U
B
L
E
D
U
T
C
H
More clues leading to the result DOUBLE DUTCH
- Bent over London wife's nonsense
- Nonsense — boast of bigamist?
- Twin meeting wife gives incomprehensible speech
- Large one, wife gives incomprehensible speech
- Bigamous nonsense?
- Bigamy? It’s incomprehensible
- What Cockney bigamist has is incomprehensible
- Cockney bigamist has this nonsense
- Nonsense, the other half as a whole?
- Paying for yourself twice — it’s incomprehensible
Buddy explains!
The straight part
We know that "nonsense" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nonsense = double dutch.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.