A dead one can't sting (6)
I believe the answer is:
nettle
'sting' is the definition.
(I know that nettle is a kind of sting)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for nettle that I've seen before include "Stinging plant; annoy" , "Annoy - stinger" , "urticaceous plant" , "it seems to flower only if dead" , "Stinging weed - pester" .)