Tahini base (6)
I believe the answer is:
sesame
'tahini base' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sesame that I've seen before include "Open ...., says the magician" , "Plant cultivated for seeds providing oil" , "Ali Baba's opening command" , "Open ...... is magic phrase for opening door in pantomime" , "Seed or oil used in cooking" .)