Goes along with a retrospective view about King George (6)
I believe the answer is:
'goes along with' is the definition.
(I've seen this in another clue)
'a retrospective view about king george' is the wordplay.
'retrospective' says the letters should be written in reverse.
'view' becomes 'see' (synonyms).
'about' means one lot of letters go next to another.
'king george' becomes 'gr' (Georgius Rex).
'see' reversed gives 'ees'.
'ees' put after 'gr' is 'grees'.
(Other definitions for agrees that I've seen before include "Is of one mind" , "Shakes hands" , "Holds the same opinion" , "Accedes or concurs" , "is in accord" .)