Excused for having caused an explosion (3,3)
I believe the answer is:
let off
'excused' is the definition.
(thesaurus)
'for having caused an explosion' is the wordplay.
I cannot really understand how this works, but
'for' could be 'to' (eg both can mean 'in the opinion of') and 'to' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for let off that I've seen before include "given a reprieve" , "Refrain from punishing, or ignite a firework" , "Fired" , "Not punished at all" , "Allow to go free; discharge" .)