Days of ___ (long ago) (4)
I believe the answer is:
'days of long ago' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yore that I've seen before include "Long ago (poetic)" , "Bygone time" , "Yesteryear" , "Formerly, of long ago" , "Old usage for formerly, as in days of. . ." .)