Troublesome, annoying (5)
I believe the answer is:
pesky
This clue is a double definition.
'troublesome' is the first definition.
(I've seen this in another clue)
'annoying' is the second definition.
(I know that annoying can be written as pesky)
(Other definitions for pesky that I've seen before include "Annoying (informal)" , "Annoying - troublesome" , "Bothersome" .)