### Clue: It's sleep-inducing to write note on 40% of curriculum (8)
### Answer: PENDULUM 
 ### Explanation: Definition: It's sleep-inducing
 PEN(to write) + D(a note in the musical scale) **plus**(on) **the last 4 out of 10 letters of**(40% of) "curriculum".
Defn: Something that could induce sleep (or a hypnotic state) by its rhythmic movement.