Reportedly modern, from the time of plague (8)
I believe the answer is:
nuisance
'plague' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for nuisance that I've seen before include "It causes inconvenience or annoyance" , "Source of irritation, person or thing" , "Annoying person/thing" , "Trouble" , "Pest or irritation" .)