Huge electronic image (4)
I believe the answer is:
epic
'huge' is the definition.
(I've seen this before)
'electronic image' is the wordplay.
'electronic' becomes 'e' (as in e-mail or e-books).
'image' becomes 'pic' (short for picture).
'e'+'pic'='EPIC'
(Other definitions for epic that I've seen before include "eg The Iliad" , "imposing" , "Long literary work about great events" , "Heroic narrative verse" , "Heroic poem, film" .)