Herb of the mint family (5)
I believe the answer is:
basil
'herb of the mint family' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for basil that I've seen before include "Aromatic leaves, used fresh or dried" , "A herb; Cardinal --- Hume" , "Herb (from Fawlty Towers?)" , "comic character" , "Culinary herb" .)