Calm and collected (4-9)
'calm and collected' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sedate that I've seen before include "Calm, unhurried" , "Calm or spectral appartition" , "grave" , "Collected" , "Dignified and subdued" .)
(Other definitions for self-possessed that I've seen before include "In control of one's feelings" , "Composed, confident" .)