Drink hot Italian stuff on the way up (7)
I believe the answer is:
martini
'drink' is the definition.
(martini is a kind of drink)
'hot italian stuff on the way up' is the wordplay.
'hot' becomes 'in' (both can mean fashionable).
'italian' becomes 'it' (abbreviation for Italian).
'stuff' becomes 'ram' (ramming is a kind of stuffing).
'on the way up' says the letters should be written in reverse.
'in'+'it'+'ram'='initram'
'initram' backwards is 'MARTINI'.
(Other definitions for martini that I've seen before include "obtained from a bottle" , "tipple" , "In glass, one's dry" , "James Bond's drink of choice" , "Cocktail of gin and dry vermouth" .)