The most common and most likely answer to this crossword clue is the 7 letter word APHONIA
A
P
H
O
N
I
A
More clues leading to the result APHONIA
Buddy explains!
The straight part
We know that "No sound reason" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case no sound reason = aphonia.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 APHONIA mean?
APHONIA noun- Loss of voice; the inability to speak.