Frees from an obligation (7)
I believe the answer is:
exempts
'frees from an obligation' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for exempts that I've seen before include "Grants immunity to" , "Lets off" , "Excuses" , "Frees from liability" , "Frees from obligation, say jury service" .)