The most common and most likely answer to this crossword clue is the 10 letter word SOUNDTRACK
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result SOUNDTRACK
- Wholesome to follow the progress of accompanying music
- What rail services need accompanying words and music?
- Reliable course to produce music for film
- Recording of Logical Song
- Good place for running film music
- Healthy dog’s part in film?
- Healthy dog that wasn’t attached to early movies
- Supporting music in reliable way
- Groundsmen may be paid to deliver this recording
- Excellent way to make theme music
Buddy explains!

The straight part
We know that "Supporting music" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supporting music = soundtrack.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 SOUNDTRACK mean?
SOUNDTRACK noun- A narrow strip running down a movie film that carries the recorded sound in synchronization with the pictures.
- The sound (especially the music) component of a movie, video game, etc.
- A recording of such music for sale.
- Background sounds that are part of a bigger event.
- To provide, or to act as the sound or music component of a film