"Fee, fi, fo, fum" caller (4)
I believe the answer is:
ogre
'fee fi fo fum caller' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ogre that I've seen before include "Ergo (anag.)" , "Terrifying person" , "Fairy tale monster" , "Terrifying giant" , "stern one who inspires fear" .)