The most common and most likely answer to this crossword clue is the 12 letter word MISPRONOUNCE
I've seen this crossword clue in The Sunday Telegraph
M
I
S
P
R
O
N
O
U
N
C
E
More clues leading to the result MISPRONOUNCE
Buddy explains!

The straight part
We know that "don’t sound right" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case don’t sound right = mispronounce.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 MISPRONOUNCE mean?
MISPRONOUNCE verb- To pronounce (a word, phrase, etc.) incorrectly.