Mischievous child, one having no fear of consequences (8)
I believe the answer is:
impunity
'no fear of consequences' is the definition.
I can't judge whether this defines the answer.
'mischievous child one' is the wordplay.
'mischievous child' becomes 'imp' (imp can mean a misbehaving child).
'one' becomes 'unity' (synonyms).
'imp'+'unity'='IMPUNITY'
'having' acts as a link.
Can you help me to learn more?
(Other definitions for impunity that I've seen before include "Rascal, by agreement, gets exemption" , "Protection from blame" , "Freedom from punishment" , "Complete protection from unpleasant consequences" , "impossibility of punishment" .)