Calm and peaceful hotel -- a lucky town, oddly (7)
I believe the answer is:
halcyon
'calm and peaceful' is the definition.
(I've seen this before)
'hotel a lucky town oddly' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'oddly' indicates alternate letters.
'lucky'+'town'='luckytown'
The alternate letters of 'luckytown' are 'lcyon'.
'h'+'a'+'lcyon'='HALCYON'
(Other definitions for halcyon that I've seen before include "Poetic name for kingfisher" , "Any loch? (anag)" , "Happy and carefree" , "Idyllic" , "Serene" .)