The most common and most likely answer to this crossword clue is the 7 letter word PHONICS
I've seen this crossword clue in Financial Times
P
H
O
N
I
C
S
Buddy explains!
The straight part
We know that "science of sound" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case science of sound = phonics.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 PHONICS mean?
PHONICS noun- The study of how the sounds of words are represented by spelling.
- A method of teaching elementary reading based on the phonetic interpretation of normal spelling.
- Phonetics.
- Acoustics.