Reminder of the past (7)
I believe the answer is:
memento
'reminder of the past' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for memento that I've seen before include "Keepsake or souvenir" , "Souvenir, reminder of past event" , "Reminder that death is inevitable" , "A reminder of death - . . . . . . . mori" , "Souvenir, something to remember by" .)