Reviewed the rent, including the last computer system (8)
I believe the answer is:
ethernet
'computer system' is the definition.
(I've seen this before)
'reviewed the rent including the last' is the wordplay.
'reviewed' is an anagram indicator (letters reviewed or revised).
'including' indicates putting letters inside.
'last' suggests the final letters.
The last letter of 'the' is 'e'.
'the'+'rent'='therent'
'therent' is an anagram of 'ethernt'.
'ethernt' enclosing 'e' is 'ETHERNET'.
(Other definitions for ethernet that I've seen before include "comms system" , "Network of a number of computers" , "Local area computer network" , "Communication system" , "System connecting several computers" .)