### Clue: Band, very quiet otherwise, introducing piece of music at appropriate time (9)
### Answer: OPPORTUNE 
 ### Explanation: Definition: at appropriate time
 O(letter representing a ring/a band) + PP(abbrev. for "pianissimo", musical direction to play very softly/very quietly) + OR(otherwise, as in "you do this or I will do that") **plus**(introducing) TUNE(a piece of music).