Herb, guru (4)
I believe the answer is:
sage
I believe this clue is a double definition.
'herb' is the first definition.
(sage is a kind of herb)
'guru' is the second definition.
(synonyms)
(Other definitions for sage that I've seen before include "Feature of herb garden" , "Velvety-leaved herb" , "A herb or a guru" , "cheesemongers associate with Derby" , "Herb used in cooking" .)