Popular nightclub where trouble is anticipated (3,4)
I believe the answer is:
hot spot
This clue is a double definition.
'popular nightclub' is the first definition.
(I've seen this before)
'where trouble is anticipated' is the second definition.
(Other definitions for hot spot that I've seen before include "Popular nightclub" , "volatile situation" , "Place of significant danger" , "Where danger lurks" , "Site of unpredictable volcanic activity" .)