Something advantageous and ritzy almost (4)
I believe the answer is:
plus
'something advantageous' is the definition.
'ritzy almost' is the wordplay.
'ritzy' becomes 'plush'.
'almost' means to remove the last letter (most of the word but not all of it).
'plush' with its final letter taken off is 'PLUS'.
'and' acts as a link.
(Other definitions for plus that I've seen before include "Additional" , "credit" , "In addition, also" , "sign of more to come" , "As well as" .)