Celestial phenomenon (7)
I believe the answer is:
eclipse
'celestial phenomenon' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eclipse that I've seen before include "The obscuring of one celestial body by another" , "Dull time for male duck" , "Surpass in achievement" , "Black out" , "Deprive of prominence" .)