Dreadful experience on different drug for morning or evening, perhaps (5,5)
I believe the answer is:
Here is my best explanation:
'morning or evening perhaps' is the definition.
'dreadful experience on different drug' is the wordplay.
'dreadful experience' becomes 'hell'.
'on' means one lot of letters go next to another.
'different' becomes 'other' ('other' can be similar in meaning to 'different').
'drug' becomes 'e' (e is another name for ecstasy).
'for' acts as a link.
(Other definitions for hello there that I've seen before include "Hi!" and "Good day".)