The most common and most likely answer to this crossword clue is the 11 letter word UNPALATABLE
I've seen this crossword clue in The Daily Telegraph
U
N
P
A
L
A
T
A
B
L
E
Buddy explains!
The straight part
We know that "disagreeable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case disagreeable = unpalatable.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 UNPALATABLE mean?
UNPALATABLE noun- Anything distasteful.
- Unpleasant to the taste
- (by extension) unpleasant or disagreeable