Annoying or troublesome person or thing (8)
I believe the answer is:
nuisance
I believe this is a double definition.
'annoying or troublesome person' is the first definition.
(I've seen this before)
'thing' is the second definition.
(I have seen 'Troublesome thing ' mean 'nuisance' so perhaps 'thing' could also mean 'nuisance')
(Other definitions for nuisance that I've seen before include "Annoying or troublesome person or thing" , "Pest, source of annoyance" , "One causing annoyance" , "It causes inconvenience or annoyance" , "Annoying thing/person" .)