Demonstrate, when the page gets turned over (5)
I believe the answer is:
prove
'demonstrate' is the definition.
(I know that demonstrate can be written as prove)
'the page gets turned over' is the wordplay.
'the page' becomes 'p'.
'gets' is a charade indicator (letters next to each other).
'turned' indicates an anagram.
'over' with letters rearranged gives 'rove'.
'p'+'rove'='PROVE'
'when' acts as a link.
(Other definitions for prove that I've seen before include "Demonstrate beyond doubt" , "Show to be true" , "Establish the validity of" , "13 [SHOW]" , "Demonstrate conclusively" .)