E-books doubled English understanding (7)
I believe the answer is:
entente
'understanding' is the definition.
(entente is a kind of understanding)
'e-books doubled english' is the wordplay.
'books' becomes 'nt' (New Testament).
'doubled' indicates the doubling of some letters.
'english' becomes 'e' (abbreviation).
'e'+'nt'='ent'
'ent' duplicated is 'entent'.
'entent'+'e'='ENTENTE'
(Other definitions for entente that I've seen before include "Harmony" , "that brings nations closer together" , "A friendly underatanding between countries, may be cordiale" , "Agreement between governments" , "Friendly agreement between states" .)