Annoying or troublesome person (8)
I believe the answer is:
nuisance
'annoying or troublesome person' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nuisance that I've seen before include "It causes inconvenience or annoyance" , "Irritant or botheration" , "troublesome type" , "Annoying or troublesome person or thing" , "Pest, source of annoyance" .)