Junkie turned over European dude to get online identity (8)
I believe the answer is:
username
'online identity' is the definition.
(I've seen this before)
'junkie turned over european dude' is the wordplay.
'junkie' becomes 'user' (I've seen this before).
'turned over' says the letters should be written backwards.
'european' becomes 'e' (abbreviation e.g. EU).
'dude' becomes 'man' (I've seen this before).
'e'+'man'='eman'
'eman' back-to-front is 'name'.
'user'+'name'='USERNAME'
'to get' acts as a link.
(Other definitions for username that I've seen before include "One's identifier on a computer" , "Computer log-in requirement" , "Person's computer ID" , "Login ID" , "Something needed for logging in" .)