Aurora, that early bird (4)
I believe the answer is:
dawn
'aurora' is the definition.
(synonyms)
'early bird' is the wordplay.
I cannot really understand how this works, but
'bird' could be 'daw' (daw is a kind of bird) and 'daw' is present in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'that' acts as a link.
Can you help me to learn more?
(Other definitions for dawn that I've seen before include "Begin to appear" , "fresh start" , "Light in East" , "beginning" , "Sunrise" .)