Monster therefore arises (4)
I believe the answer is:
ogre
'monster' is the definition.
(fairy tale monster)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ogre that I've seen before include "Wicked giant" , "Man-eating monster of fairy tales" , "character in 'Puss in Boots'" , "Bogeyman" , "Fairy tale giant" .)