IT system with two numbers, the second raised (8)
I believe the answer is:
ethernet
'it system' is the definition.
'two numbers the second raised' is the wordplay.
'two numbers' means two replacements for 'number'.
'number' becomes 'ether' (I've seen this in other clues).
'number' becomes 'n'.
'the second raised' becomes 'et' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ether'+'n'+'et'='ETHERNET'
'with' is the link.
(Other definitions for ethernet that I've seen before include "Local area computer network" , "food" , "comms system" , "Computer system" , "Communication system" .)