Second hearing (4)
I believe the answer is:
This clue might be a double definition.
'second' is the first definition.
(I've seen this in another clue)
'hearing' is the second definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
Can you help me to learn more?
(Other definitions for echo that I've seen before include "Repeat or reverberate" , "Rebounding sound" , "Ape" , "Greek girl in love with Narcissus" , "A natural sound reflection" .)