Plunges into low haunts? (5)
I believe the answer is:
dives
'plunges' is the definition.
('dive' can be a synonym of 'plunge')
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for dives that I've seen before include "Plunges head first" , "Rich man's" , "Sleazy bars" , "Seedy nightclubs" , "rich man used" .)