Old version of The Mirror put on electronic viewing device (8)
I believe the answer is:
eyeglass
'viewing device' is the definition.
'old version of the mirror put on electronic' is the wordplay.
'old version of the' becomes 'ye' ('ye' resembles a historical spelling of 'the').
'mirror' becomes 'glass' (glass is a kind of mirror).
'put on' says to put letters next to each other.
'electronic' becomes 'e' (as in e-mail or e-books).
'ye'+'glass'='yeglass'
'yeglass' put after 'e' is 'EYEGLASS'.
(Other definitions for eyeglass that I've seen before include "Lens for aiding defective vision" , "Aid to vision" , "Monocle, or spectacles in plural" .)