Grieving for break of day, we hear (8)

I believe the answer is:

mourning

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

'grieving' is the definition.
(I know that grieving can be written as mourning)

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

(Other definitions for mourning that I've seen before include "Feeling loss" , "Sorrowing" , "Grieving" , "wearing black" , "Black clothing" .)

I've seen this clue in The Telegraph.

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