Restaurant employee dropping one drink (5)
I believe the answer is:
water
'drink' is the definition.
(water is an example)
'restaurant employee dropping one' is the wordplay.
'restaurant employee' becomes 'waiter' (restaurants employee waiters).
'dropping' suggests deleting specific letters.
'one' becomes 'i' (Roman numeral).
'waiter' with 'i' taken away is 'WATER'.
(Other definitions for water that I've seen before include "Aqua" , "Commonplace drink" , "Superior's full of it" , "Diamond quality" , "Inundate" .)