The most common and most likely answer to this crossword clue is the 5 letter word CREAK
C
R
E
A
K
Buddy explains!
The straight part
We know that "sound" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sound = creak.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 CREAK mean?
CREAK noun- The sound produced by anything that creaks; a creaking.
- To make a prolonged sharp grating or squeaking sound, as by the friction of hard substances.
- To produce a creaking sound with.
- To suffer from strain or old age.