After work, quiet or music is timely (9)
I believe the answer is:
opportune
'is timely' is the definition.
(similar in meaning)
'after work quiet or music' is the wordplay.
I cannot really see how this works, but
'work' could be 'op' (common abbreviation for 'opus') and 'op' is found in the answer.
'quiet' could be 'p' (music symbol for 'piano', ie soft or quiet) and 'p' is found within the answer.
'or' is present in the answer.
'music' could be 'tune' (tune is a kind of music) and 'tune' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for opportune that I've seen before include "Timely, advantageous moment" , "Well-timed" , "Occurring at a fitting time" , "fit" , "Timely and convenient" .)