Surprise publicity event not carrying through (4)
I believe the answer is:
stun
'surprise' is the definition.
(stunning is a kind of surprising)
'publicity event not carrying through' is the wordplay.
I cannot really see how this works, but
'not' could be 'un' (prefix meaning 'not') and 'un' is present in the answer.
The remaining letters 'st' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for stun that I've seen before include "Daze, knock senseless" , "Anaesthetise" , "Daze, stupify" , "Daze with nuts" , "Dumbfound" .)