>Happened for only one time and it won’t repeat.
>A sudden spasmodic (means – irregular burst) effort that accomplishes nothing
>One that appears promising but turns out to be disappointing or worthless
>Someone or something whose success or popularity is short-lived.
Example
>Considering their dismal past record, the win in the last match seems to be a flash in the pan
> With only one hit song, it was obvious that the young pop star was going to be just another flash in the pan