Wake-up call first for Cassandra? (8)
I believe the answer is:
alarmist
'cassandra?' is the definition.
(both can mean someone predicting disaster)
'wake-up call first' is the wordplay.
'wake-up call' becomes 'alarm' (as in an alarm clock).
'first' becomes 'ist' (ist resembles 1st).
'alarm'+'ist'='ALARMIST'
'for' acts as a link.
(Other definitions for alarmist that I've seen before include "Scary" , "Like panicking passenger" , "One may cause panic" , "One overstating danger" , "Person exaggerating danger" .)