Acquitted of having caused an explosion (3,3)
I believe the answer is:
let off
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for let off that I've seen before include "Allow to escape punishment" , "chance to avoid trouble" , "Set free without charge" , "Refrain from punishing, or ignite a firework" , "not guillotined?" .)