King George in Succession embarrassment (7)
I believe the answer is:
chagrin
'embarrassment' is the definition.
(chagrin is a kind of embarrassment)
'king george in succession' is the wordplay.
'king george' becomes 'gr' (Georgius Rex).
'in' is an insertion indicator.
'succession' becomes 'chain' (I've seen this before).
'gr' going into 'chain' is 'CHAGRIN'.
(Other definitions for chagrin that I've seen before include "Disappointment, exasperation" , "Arching with annoyed disappointment" , "Discomfiture" , "Humiliation, mortification" , "Strong feeling of embarrassment" .)