What does the cryptic crossword clue "Reliable staff one's hired to work in TV or film (8)" mean?

The wordplay uses a charade (building blocks). SOUND (synonym="SOUND") + MAN (synonym="to staff") = SOUNDMAN The answer is SOUNDMAN.

Reliable staff one's hired to work in TV or film (8)

Guardian Cryptic #29187 | 9 Across | 2023-09-28 flower