Worn-out fossil one to throw away (5)
I believe the answer is:
trite
'worn-out' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for trite that I've seen before include "Lyre string" , "used till novelty's worn off" , "(Of an idea) lacking in originality" , "repeated too often" , "all vigour is gone" .)