King George I stops for dying subject? (5)
I believe the answer is:
goner
'dying subject?' is the definition.
'king george i stops' is the wordplay.
'king george' becomes 'gr' (Georgius Rex).
'i' becomes 'one' ('one' can be a synonym of 'i').
'stops' means one lot of letters goes inside another (to stop can mean to block a gap).
'gr' going around 'one' is 'GONER'.
'for' acts as a link.
(Other definitions for goner that I've seen before include "One past helping" , "Person beyond saving" , "One beyond help" , "A has-been in distress" , "Someone beyond help" .)