Oriental sauce from Dungeness oysters (3)
I believe the answer is:
soy
'oriental sauce' is the definition.
(I've seen this before)
'from dungeness oysters' is the wordplay.
'from' indicates the answer is hidden within the clue.
'SOY' is hidden within 'dungeness oysters'.
(Other definitions for soy that I've seen before include "Oriental sauce" , "Chinese sauce" , "Dark salty sauce" , "Piquant eastern sauce" , "Sauce bean" .)