Insulting the powerful? Not exactly seemly to include a joke (4,7)
I believe the answer is:
lese majesty
'insulting the powerful?' is the definition.
(French term for insulting a monarch)
'not exactly seemly to include a joke' is the wordplay.
'not exactly' indicates anagramming the letters.
'to include' means one lot of letters goes inside another.
'joke' becomes 'jest' (synonyms).
'seemly' with letters rearranged gives 'lesemy'.
'a'+'jest'='ajest'
'lesemy' going around 'ajest' is 'LESE-MAJESTY'.
(Other definitions for lese majesty that I've seen before include "cause serious offence" , "Insulting a sovereign" .)