Royal power and might broken by witticism (7)
I believe the answer is:
majesty
'royal power' is the definition.
(I've seen this before)
'might broken by witticism' is the wordplay.
'might' becomes 'may' (I've seen this in another clue).
'broken by' indicates putting letters inside (inserted letters break into the word).
'witticism' becomes 'jest' (jest is a kind of witticism).
'may' going around 'jest' is 'MAJESTY'.
'and' is the link.
(Other definitions for majesty that I've seen before include "Stateliness" , "August impression" , "M. of H.M." , "Royal power" , "Monarch's designation" .)