Stare at torn page (4)
I believe the answer is:
gape
'stare at' is the definition.
(I've seen this in another clue)
'torn page' is the wordplay.
'torn' indicates an anagram.
'page' is an anagram of 'GAPE'.
(Other definitions for gape that I've seen before include "Stare stupidly" , "Open-mouthed stare" , "Look open-mouthed" , "Peer" , "wide opening" .)