Train user to reset a computer, finally (8)
I believe the answer is:
eurostar
'train' is the definition.
(I've seen this before)
'user to reset a computer finally' is the wordplay.
'reset' indicates anagramming the letters.
'finally' indicates one should take the final letters.
The last letter of 'computer' is 'r'.
'user'+'to'='userto'
'userto' anagrammed gives 'eurost'.
'eurost'+'a'+'r'='EUROSTAR'
(Other definitions for eurostar that I've seen before include "travel service" , "The train from England to France" , "International traveller" , "Channel tunnel rail service" , "International train" .)