Previous publicity about where carnival is held (5)
I believe the answer is:
prior
'previous' is the definition.
(prior means previous or earlier)
'publicity about where carnival is held' is the wordplay.
I cannot really see how this works, but
'publicity' could be 'pr' (abbreviation for public relations) and 'pr' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for prior that I've seen before include "Previous - religious leader" , "Deputy head of an abbey" , "Preceding" , "More important" , "figure of authority in retreat" .)