Pester, nuisance (6)
I believe the answer is:
hassle
I believe this is a double definition.
'pester' is the first definition.
(I've seen this in another clue)
'nuisance' is the second definition.
(I've seen this in another clue)
(Other definitions for hassle that I've seen before include "Informally annoy or bother" , "Harass - grief" , "(Cause) stressful annoyance (to)" , "Annoy continually" , "Difficulty - dispute" .)