The most common and most likely answer to this crossword clue is the 8 letter word ARCTURUS
I've seen this crossword clue in The Times
A
R
C
T
U
R
U
S
More clues leading to the result ARCTURUS
- Luminous discharge — constellation losing alpha star
- Luminous discharge with constellation losing alpha star
- Take in routine beast, one shining brightly
- Radiant discharge associated with constellation losing alpha star
- Star of a Roman Catholic channel backed America
- Star turn finishing early after bow before our group
- Patrick oddly ignored constellation without a red giant
- Bow before short performance by American 2
- Not the Dog-Star – Cur-Star, second in luminosity, possibly
Buddy explains!
The straight part
We know that "Star" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case star = arcturus.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.