Atmosphere in Broadstairs (3)
I believe the answer is:
air
'atmosphere' is the definition.
(synonyms)
'in broadstairs' is the wordplay.
'in' indicates a hidden word.
'AIR' can be found hidden inside 'broadstairs'.
(Other definitions for air that I've seen before include "Element; tune" , "A tune or attitude" , "Vital thing" , "Tune - mood - atmosphere" , "Song; ventilate" .)