In addition, luxurious hotel omitted (4)
I believe the answer is:
plus
'in addition' is the definition.
('plus' can be a synonym of 'in addition')
'luxurious hotel omitted' is the wordplay.
'luxurious' becomes 'plush' (I've seen this before).
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'omitted' is a deletion indicator.
'plush' with 'h' removed is 'PLUS'.
(Other definitions for plus that I've seen before include "being a little cross" , "Added extra" , "credit" , "An advantage; positive" , "advantageous" .)