Starburst? (4)
I believe the answer is:
nova
'starburst?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nova that I've seen before include "It shines" , "Sudden light increase" , "Star that suddenly increases in brightness" , "Canadian province" , "Faint star that suddenly flares into brightness and then fades again" .)