Declare to be free from blame (7)
I believe the answer is:
absolve
'declare to be free from blame' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for absolve that I've seen before include "Forgive sins" , "Declare (someone) blameless" , "Discharge" , "Exonerate" , "free of error" .)