Wise-guy king has no protective barrier (4-3)
I believe the answer is:
know-all
'wise-guy' is the definition.
'king has no protective barrier' is the wordplay.
'king' becomes 'k'.
'has' is a charade indicator (letters next to each other).
'protective barrier' becomes 'wall'.
'k'+'no'+'wall'='KNOW-ALL'
(Other definitions for know-all that I've seen before include "He always has answer" , "One who thinks they have all the answers" , "Person who behaves like encyclopedia 94-3)" , "Someone who refuses to accept advice or information from others" , "Pedantic" .)