Releases from duty (7)
I believe the answer is:
exempts
'releases from duty' 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" , "Frees from obligation, say jury service" , "Excuses" , "Frees from liability" .)