Peaceful and calm for days (7)
I believe the answer is:
halcyon
This clue might be a double definition.
'peaceful' is the first definition.
(thesaurus)
'calm for days' is the second definition.
'halcyon' can be an answer for 'calm' (thesaurus). I'm not sure about the 'for days' bit.
'and' is the link.
Can you help me to learn more?
(Other definitions for halcyon that I've seen before include "Prosperous" , "undisturbed" , "Such days are calm and happy" , "Balmy" , "Idyllically happy and peaceful" .)