Dark times for sir's announcement (6)

I believe the answer is:

nights

I'm a little stuck... Click here to teach me more about this clue!

'dark times' is the definition.
(I've seen this in another clue)

I don't understand how the remainder of the clue works.

(Other definitions for nights that I've seen before include "Dark periods" , "See 9" , "Times between days" , "Things (anag.)" , "dark times" .)

I've seen this clue in the Sydney Morning Herald.

Want a hint initially instead of a full solution? Install my app