Placid (6)
(Other definitions for docile that I've seen before include "Gentle and biddable" , "Gentle, tame" , "Gentle and tractable" , "Gentle and teachable" , "Easily managed and trainable" .)
'placid' is the definition.
(synonyms)
This is all the clue.
(Other definitions for serene that I've seen before include "Not agitated" , "Calm, untroubled" , "Totally unagitated" , "Calm and relaxed" , "Tranquil, perfectly calm" .)
'placid' 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 "Teased into being calm" , "Leisurely" , "Calm and demure" , "Collected" , "Dignified - staid" .)
'placid' is the definition.
(I know that placid can be written as equable)
This is all the clue.
(Other definitions for equable that I've seen before include "Calm, even-tempered" , "Not easily angered" , "Cool" , "composed" , "Placid; unvarying" .)