Hotel with everything in one room (4)
I believe the answer is:
hall
'one room' is the definition.
(hall is a kind of room)
'hotel with everything' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' is a charade indicator (letters next to each other).
'everything' becomes 'all' (all things).
'h'+'all'='HALL'
'in' acts as a link.
(Other definitions for hall that I've seen before include "See 21" , "Entrance area" , "Large public building" , "Building used for public assembly" , "See 1" .)