Plant with stinging hairs (6)
I believe the answer is:
nettle
'plant with stinging hairs' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nettle that I've seen before include "Sting or annoy with the plant" , "Plant with stinging hairs" , "Wild plant - annoy" , "Clasp it firmly and it will not sting" , "Upset" .)