Show disdain for bad puns about the king (5)
I believe the answer is:
spurn
'show disdain for' is the definition.
(I've seen this in another clue)
'bad puns about the king' is the wordplay.
'bad' indicates an anagram.
'about' is an insertion indicator.
'the king' becomes 'R' (abbreviation for rex, king in Latin).
'puns' is an anagram of 'spun'.
'spun' enclosing 'r' is 'SPURN'.
(Other definitions for spurn that I've seen before include "Reject scornfully, rebuff" , "Cold-shoulder" , "Slight" , "Reject advances scornfully" , "Contemptuously reject" .)