Brilliant performer in space (4)
I believe the answer is:
star
This clue could be a double definition.
'brilliant' is the first definition.
(I've seen this in other clues)
'performer in space' is the second definition.
'star' can be an answer for 'performer' (star is a kind of performer). I'm unsure of the 'in space' bit.
Can you help me to learn more?
(Other definitions for star that I've seen before include "A heavenly body or film favourite" , "Asterisk" , "A night light?" , "Outstanding person" , "Leading character" .)