Not into horrific executions, providing explanation (6)

I believe the answer is:

excuse

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'explanation' is the definition.
(I know that excuse is a type of defence)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for excuse that I've seen before include "Forgive - allow to pass - plea" , "Forgive - apology" , "A self-justification" , "Allow to be released from a duty" , "Grant an exemption or justify" .)

I've seen this clue in The Irish Times.

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