We hear it's of timely significance (3)
I believe the answer is:
pip
'significance' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for pip that I've seen before include "Small fruit seed" , "Defeat at the last moment - . . . at the post" , "Small hard seed" , "one signals lieutenant" , "Philip" .)