It's silly making a lot of noise when the light goes out (5)
I believe the answer is:
daffy
'it's silly' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for daffy that I've seen before include "Bonkers" , "Cuckoo" , "Silly, mildly eccentric" , "Crazy" , "Silly, eccentric (colloq.)" .)