Hi-tech Tokyo corporation on the rise for very long time (4)
I believe the answer is:
ages
'very long time' is the definition.
(I've seen this before)
'hi-tech tokyo corporation on the rise' is the wordplay.
'hi-tech tokyo corporation' becomes 'SEGA'.
'on the rise' shows that the letters should be reversed in order.
'sega' backwards is 'AGES'.
'for' acts as a link.
(Other definitions for ages that I've seen before include "Awfully long time" , "Donkey's years" , "Times" , "Long periods" , "Indefinitely long time" .)