Trouble in the past surrounding King George (5)
I believe the answer is:
aggro
'trouble' is the definition.
(I've seen this before)
'past surrounding king george' is the wordplay.
'past' becomes 'ago' ('ago' can be similar in meaning to 'past').
'surrounding' indicates putting letters inside.
'king george' becomes 'gr' (Georgius Rex).
'ago' enclosing 'gr' is 'AGGRO'.
'in the' is the link.
(Other definitions for aggro that I've seen before include "Difficulties (sl.)" , "Grief" , "Violence - obstructiveness" , "Violent disturbance" , "Slang for deliberate trouble-making" .)