Regret finding a herb (3)
I believe the answer is:
rue
This clue is a double definition.
'regret' is the first definition.
(to rue something is to regret it)
'a herb' is the second definition.
(rue is a herb)
'finding' is the link.
(Other definitions for rue that I've seen before include "At one time, pity" , "Regret or repent" , "Be regretful" , "Deplore" , "Feel sorry" .)