Backward woodworm found in the herb (8)
I believe the answer is:
wormwood
'backward woodworm found in the herb' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for wormwood that I've seen before include "Woodworm found in kind of timber" , "(Plant used for) absinthe" , "Backward woodworm found in the herb" , "Having the gall" , "Source of absinthe" .)