Restaurant employee, one spilled Adam's wine (5)
I believe the answer is:
water
'adam's wine' is the definition.
(Adam's wine can informally mean water)
'restaurant employee one spilled' is the wordplay.
'restaurant employee' becomes 'waiter' (restaurants employee waiters).
'one' becomes 'i' (Roman numeral).
'spilled' suggests deleting specific letters (some letters spill out).
'waiter' with 'i' taken away is 'WATER'.
(Other definitions for water that I've seen before include "Aqua" , "Common fluid" , "Commonest fluid" , "Essential liquid" , "It's to be found in puddles, pools and ponds" .)