In breaking the law, Oscar is being naughty! (4)
I believe the answer is:
awol
'being naughty' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?
'in breaking the law oscar' is the wordplay.
'in' is an insertion indicator.
'breaking' is an anagram indicator.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'law' anagrammed gives 'awl'.
'awl' placed around 'o' is 'AWOL'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for awol that I've seen before include "On the lam" , "Absent without leave (abbrev.)" , "Absent without permission, in short" , "Not present when supposed to be" , "Missing without permission" .)