Calm and demure (6)
I believe the answer is:
sedate
'calm and demure' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sedate that I've seen before include "not disturbed by passion or excitement?" , "Staid - tranquillise" , "Give calming drug to" , "Dignified and sombre" , "Slow" .)