I'm cavorting with Satan for endurance (7)
I believe the answer is:
stamina
'endurance' is the definition.
(I know that endurance can be written as stamina)
'i'm cavorting with satan' is the wordplay.
'cavorting with' indicates anagramming the letters.
'im' with its letters mixed up with 'satan' makes 'STAMINA'.
'for' acts as a link.
(Other definitions for stamina that I've seen before include "Ability to keep going" , "Ability for sustained effort" , "Energy and staying power" , "The ability to sustain prolonged physical or mental effort" , "capacity to endure" .)