Good time for report (4)
I believe the answer is:
boom
This clue is a double definition.
'good time' is the first definition.
(I've seen this in another clue)
'report' is the second definition.
(both can mean a loud noise)
'for' is the link.
(Other definitions for boom that I've seen before include "Crash" , "Harbour barrier" , "Big bang sound" , "Prosperous time - sound of explosion - yachting spar" , "Bonanza; roar" .)