Badger in fatal outbreak (6)
I believe the answer is:
plague
This clue is a double definition.
'badger' is the first definition.
(I know that badger is a more specific form of bedevil)
'fatal outbreak' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for plague that I've seen before include "Epidemic disease with high mortality" , "Widespread, contagious and destructive disease" , "Deadly pestilence" , "Epidemic disease with a high death rate" , "Pester with deadly disease" .)