Star briefly welcomes unknown extras (4)
I believe the answer is:
byes
'extras' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for byes that I've seen before include "Greedy person; seabird" , "In cricket, runs scored from balls that pass the batman without being hit" , "Runs wicketkeeper concedes" , "Cricket extras" , "tournament passes" .)