You and I stood by King George and got bigger (4)
I believe the answer is:
grew
'got bigger' is the definition.
(I've seen this in another clue)
'you and i stood by king george' is the wordplay.
'you and i' becomes 'we'.
'stood' shows that the letters should be reversed in order (I've seen 'standing' mean this (in a down clue, letters stand up)).
'by' is a charade indicator (letters next to each other).
'king george' becomes 'gr' (Georgius Rex).
'we' written backwards gives 'ew'.
'ew' put after 'gr' is 'GREW'.
'and' acts as a link.
(Other definitions for grew that I've seen before include "Got bigger" , "Cultivated'" , "Became larger" , "Developed, matured" , "Multiplied" .)