Annoy; worry (6)
I believe the answer is:
bother
I believe this clue is a double definition.
'annoy' is the first definition.
(I know that annoy can be written as bother)
'worry' is the second definition.
(I've seen this before)
(Other definitions for bother that I've seen before include "Discommode, annoy" , "Annoy or pester" , "Fuss, ado" , "Fuss and irritant" , "Take the trouble to do something" .)