500 waxwings regularly fly away when days break (5)

I believe the answer is:

dawns

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

'fly away when days break' is the definition.
I can't judge whether this definition defines the answer.

'500 waxwings regularly' is the wordplay.
'500' becomes 'D' (Roman numeral for 500).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternating letters of 'waxwings' are 'awns'.
'd'+'awns'='DAWNS'

Can you help me to learn more?

(Another definition for dawns that I've seen is " gets lighter".)

I've seen this clue in The Independent.

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