Poetic preposition (3)
'poetic preposition' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ere that I've seen before include "Before (in poetry)" , "One who steals" , "Before (lit.)" , "Archaic word for before - a palindrome" , "Before (poetic)" .)
(Another definition for oer that I've seen is " Above (poetic)".)