Herb of mint family (5)
I believe the answer is:
thyme
'herb of mint family' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for thyme that I've seen before include "Aromatic ingredient" , "Aromatic shrub" , "Ingredient in cooking" , "Culinary adjunct" , "A herb; sounds like prison sentence" .)