Great fear or apprehension (5)
I believe the answer is:
dread
I believe this clue is a double definition.
'great fear' is the first definition.
(I've seen this in another clue)
'apprehension' is the second definition.
(I know that apprehension can be written as dread)
(Other definitions for dread that I've seen before include "Apprehensive fear" , "Anticipate with fear" , "Anticipate with horror" , "great anxiety" , "Great fear or apprehension" .)