Run rings round Oxford University idiot (6)
I believe the answer is:
outwit
'run rings round' is the definition.
(to run rings round someone is to outsmart them)
'oxford university idiot' is the wordplay.
'oxford university' becomes 'OU'.
'idiot' becomes 'twit' (both can mean a stupid person).
'ou'+'twit'='OUTWIT'
(Other definitions for outwit that I've seen before include "Dupe" , "To fox" , "Surpass in ingenuity" , "Show more ingenuity than" , "Hoodwink" .)