Provoke fellows to take supplement (6)
I believe the answer is:
madden
'provoke' is the definition.
(I know that madden is a more specific form of the action bedevil)
'fellows to take supplement' is the wordplay.
'fellows' becomes 'men' (fellow can mean a man).
'to take' is an insertion indicator (inserted letters are taken in).
'supplement' becomes 'add' (I've seen this before).
'men' enclosing 'add' is 'MADDEN'.
(Other definitions for madden that I've seen before include "Enrage, make furious" , "anger" , "Infuriate or drive insane" , "Become extremely angry" , "Make very angry, infuriate" .)