Resin found in herbal sample (6)
I believe the answer is:
balsam
'resin' is the definition.
(balsam is a kind of resin)
'in herbal sample' is the wordplay.
'in' indicates a hidden word.
'BALSAM' is hidden within 'herbal sample'.
'found' is the link.
(Other definitions for balsam that I've seen before include "flowering plant" , "Fragrant medicinal gum from tree" , "Resin-yielding tree" , "Mal, BAs can produce a healing agent" , "Fragrant medicinal plant resin" .)