They say season with herb (5)
I believe the answer is:
thyme
'herb' is the definition.
(thyme is a kind of herb)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for thyme that I've seen before include "something fragrant?" , "Minty herb" , "Aromatic ingredient" , "Ingredient in cooking" , "Small shrub: leaves used to season food" .)