Common weed bug (6)
I believe the answer is:
nettle
I believe this clue is a double definition.
'common weed' is the first definition.
(I've seen this before)
'bug' is the second definition.
(thesaurus)
(Other definitions for nettle that I've seen before include "Irritate, annoy" , "it seems to flower only if dead" , "anger?" , "Grasp it firmly and it will not sting" , "To be annoying" .)