Fail miserably (4)
I believe the answer is:
bomb
'fail miserably' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bomb that I've seen before include "fortune" , "Unpleasant surprise" , "Flop - load of money" , "Great deal of money (slang)" , "Big bucks - flop" .)