Plant that has done real damage (8)
I believe the answer is:
oleander
'plant' is the definition.
The answer is an example.
'done real damage' is the wordplay.
'damage' indicates anagramming the letters (I've seen 'damaged' mean this).
'done'+'real'='donereal'
'donereal' is an anagram of 'OLEANDER'.
'that has' is the link.
(Other definitions for oleander that I've seen before include "'Adorn eel, badly, with this shrub (8)'" , "bloomer" , "No leader, oddly, for the flowering shrub" , "Evergreen flowering shrub from olden era" , "Flowering shrub from olden era, oddly" .)