Super star (4)
I believe the answer is:
nova
'super star' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nova that I've seen before include "Star that suddenly increases in brightness" , "Star showing a sudden, brief increase in luminosity" , "Kind of star" , "It shines" , "Star that ejects a cloud, thus becoming brighter" .)