Pester, torment (6)
I believe the answer is:
harass
I believe this clue is a double definition.
'pester' is the first definition.
(I know that pester is a more specific form of the action bedevil)
'torment' is the second definition.
(I know that torment is a more specific form of the action harass)
(Other definitions for harass that I've seen before include "Nag" , "Trouble and annoy continually" , "Harry" , "Bother and annoy continuously" , "Persistently torment" .)