Vinegar accompaniment (3)
I believe the answer is:
oil
'vinegar accompaniment' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oil that I've seen before include "Fuel, lubricant" , "what can be seen on iceberg" , "SECOND PART OF 23" , "Anoint" , "Liquid fuel" .)