The most common and most likely answer to this crossword clue is the 7 plus 9 letter word TRUMPET VOLUNTARY
I've seen this crossword clue in The Times
T
R
U
M
P
E
T
V
O
L
U
N
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A
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Y
Buddy explains!
The straight part
We know that "that’s music to our ears" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that’s music to our ears = trumpet voluntary.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.