Anxious uncertainty (8)
I believe the answer is:
suspense
'anxious uncertainty' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for suspense that I've seen before include "Uncertain state" , "Feeling of excitement or anxiety about what might happen" , "State of uncertainty or excitement" , "State of anxiety while waiting" , "Tense uncertainty" .)