Staff drinking company wine (5)
I believe the answer is:
macon
'wine' is the definition.
(macon is a kind of wine)
'staff drinking company' is the wordplay.
'staff' becomes 'man' (as in staffing or manning a particular place).
'drinking' means one lot of letters goes inside another (inserted letters are consumed or drunk).
'company' becomes 'co' (abbreviation).
'man' placed around 'co' is 'MACON'.
(Other definitions for macon that I've seen before include "Drink" , "Variety of Burgundy" , "A heavy Burgundy" , "red" , "French wine district" .)