One rising at dawn (3)
I believe the answer is:
sun
'one rising at dawn' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sun that I've seen before include "Nearest star to Earth" , "Star around which the earth travels" , "Louis XIV of France was known as The . . . King" , "Shiny" , "Warmer" .)