Talk deliriously (4)
I believe the answer is:
rave
'talk deliriously' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rave that I've seen before include "Modern youth dance - sounds hysterical" , "Illegal party; talk madly" , "Talk wildly and angrily" , "Wild party; go mad" , "Rant about an all-night dance party?" .)