Stare at crumpled page (4)
I believe the answer is:
gape
'stare at' is the definition.
(I've seen this in another clue)
'crumpled page' is the wordplay.
'crumpled' is an anagram indicator (a crumbled or damaged version of the letters).
'page' anagrammed gives 'GAPE'.
(Other definitions for gape that I've seen before include "Look at with wide-open mouth" , "Look open-mouthed" , "Yawn" , "Look with mouth wide open" , "Open-mouthed stare" .)