Concoct a brief act that goes wrong (9)
I believe the answer is:
fabricate
'concoct' is the definition.
(fabricating is a kind of concocting)
'a brief act that goes wrong' is the wordplay.
'that goes wrong' indicates an anagram.
'a'+'brief'+'act'='abriefact'
'abriefact' is an anagram of 'FABRICATE'.
(Other definitions for fabricate that I've seen before include "Invent or manufacture a story" , "Construct or invent" , "Invent, make up" , "forge" , "Tell lies" .)