"Scream" star Campbell (4)
I believe the answer is:
neve
'scream star campbell' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for neve that I've seen before include "Mass of ice" , "Not ever." , "Snow on a glacier, not yet turned to ice" , "Type of snow on top of a glacier" , "A field of granular snow" .)