Both sides in Highbury perhaps useful (5)
I believe the answer is:
handy
'useful' is the definition.
(handy can mean useful or convenient)
I don't understand how the rest of the clue works.
(Other definitions for handy that I've seen before include "Near; useful" , "Useful and convenient" , "Convenient summary" , "Local - nearby" , "Dexterous" .)