Spice used in pickling (8)
I believe the answer is:
tarragon
'spice used in pickling' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tarragon that I've seen before include "(Aromatic plant producing) herb" , "cooking ingredient" , "Aromatic herb used in cooking" , "Arrogant sort of herb" , "Strangely arrogant herb" .)