A page torn wide open (5)
I believe the answer is:
agape
'wide open' is the definition.
(I've seen this before)
'a page torn' is the wordplay.
'torn' indicates an anagram.
'page' with letters rearranged gives 'gape'.
'a'+'gape'='AGAPE'
(Other definitions for agape that I've seen before include "the love of God!" , "love a Christian shows" , "love feast" , "Christian feast" , "(Of mouth) wide open" .)