Pour wine into another container (6)
I believe the answer is:
'pour wine into another container' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for decant that I've seen before include "Pour from bottle into table container, say wine" , "Pour wine from one container to another to remove the sediment" , "Pour wine from bottle to carafe" , "Take (wine) off lees" , "Pour wine from bottle into table vessel" .)