Such a preview will give information (5)
I believe the answer is:
sneak
'such a preview' is the definition.
(sneak preview is a kind of preview)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for sneak that I've seen before include "Snitcher" , "To go stealthily" , "Go furtively - inform on another child" , "peach" , "thief" .)