Palindromic poetic preposition (3)
I believe the answer is:
ere
'palindromic poetic preposition' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ere that I've seen before include "Before (literary)" , "One who steals" , "Before (lit.)" , "Before, poetically" , "Old word for before" .)