Some dog reared to be monster (4)
I believe the answer is:
ogre
'monster' is the definition.
('ogre' can be a synonym of 'monster')
'some dog reared to' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'OGRE' can be found hidden inside 'dog reared to'.
'be' is the link.
(Other definitions for ogre that I've seen before include "The giant is some goer" , "Has a monstrous role" , "Giant of folklore who ate humans" , "terrible person" , "Cruel and wicked person" .)