Save monarch -- like George III? (7)
I believe the answer is:
barking
'like george iii?' is the definition.
(mad king)
'save monarch' is the wordplay.
'save' becomes 'bar' (I've seen this before).
'monarch' becomes 'king' (king is a kind of monarch).
'bar'+'king'='BARKING'
(Other definitions for barking that I've seen before include "6D 5A [TUBE STATION]" , "London suburb ..." , "Dog may be" , "up the pole" , "Mad - town forming a London borough with Dagenham" .)