Calm and peaceful, as any loch could be (7)
I believe the answer is:
halcyon
'calm and peaceful' is the definition.
(halcyon can mean calm or idyllic)
'any loch could be' is the wordplay.
'could be' is an anagram indicator.
'any'+'loch'='anyloch'
'anyloch' with letters rearranged gives 'HALCYON'.
'as' is the link.
(Other definitions for halcyon that I've seen before include "Peaceful; golden" , "undisturbed" , "Calm and happy - kingfisher" , "Such days are calm and happy" , "Prosperous" .)