Monsters (5)
'monsters' is the definition.
(ogre is a type of monster)
This is all the clue.
(Other definitions for ogres that I've seen before include "Beasts" , "Monstrous giants and man-eaters" , "Fairytale giants" , "Gorse (anag.)" , "huge figures" .)
(Another definition for inc that I've seen is " Including (abbrev.)".)