Good time for a 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 a' acts as a link.
(Other definitions for boom that I've seen before include "time of 22 [PROSPERITY]" , "Cry of the bittern" , "Big bang sound" , "When business is great, opposite to bust" , "Loud noise - business increase" .)