Good time for resonance (4)
I believe the answer is:
boom
'good time' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for boom that I've seen before include "The noise of increased business activity?" , "Pick up big" , "Deep sound; spar" , "When business is great, opposite to bust" , "Time of great prosperity - hear the sound" .)