Good time for resonance (4)
I believe the answer is:
boom
'good time' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder 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" .)