Dismal amount of herbs? (6)
I believe the answer is:
rueful
'dismal' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
(Other definitions for rueful that I've seen before include "Melancholy" , "Regretful" , "Regretting" , "Filled with regret" , "Expressing wry regret" .)