### Clue: Guaranteed to support note to oneself (4-5)
### Answer: ROCK-SOLID 
 ### Explanation: Definition: Guaranteed
 ROCK(a support;a person or thing that can be depended on or provides a firm foundation) + SOL(so;the syllable for the note in the diatonic musical scale).
Defn: … to withstand and not change, fail or collapse.