Australis or Borealis? (6)
I believe the answer is:
aurora
'australis or borealis?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aurora that I've seen before include "Orange" , "Roman goodess of the dawn" , "Ship that turned red" , "Dawn goddess; polar lights" , "Atmospheric phenomenon consisting of bands of light" .)