Herb sachet (7,5)
I believe the answer is:
bouquet garni
'herb sachet' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bouquet garni that I've seen before include "Bunch of herbs for stew" , "Herb sachet" , "Small bag of herbs - quaint brogue (anag)" , "Herb bunch in stew" , "stew flavouring" .)