Terrible experience with love? I'm surprised (5)
I believe the answer is:
hello
'i'm surprised' is the definition.
('hello' can be an expression of surprise)
'terrible experience with love?' is the wordplay.
'terrible experience' becomes 'hell' (hell can mean an ordeal or trauma).
'with' is a charade indicator (letters next to each other).
'love?' becomes 'o' (love means zero in tennis).
'hell'+'o'='HELLO'
(Other definitions for hello that I've seen before include "royals dominate its pages?" , "opener?" , "Welcome" , "Look at that" , "Hi, howdy" .)