Idyllic and serene (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
tranquil
(Other definitions for tranquil that I've seen before include "Peaceful and serene" , "Free from disturbance" , "Calm, placid, still" , "like Othello's mind before Iago's treachery" , "Calm and undisturbed, at peace" .)