Blooper (5)
'blooper' is the definition.
(I know that gaffe is a type of blooper)
This is all the clue.
(Other definitions for gaffe that I've seen before include "Remark one wishes unmade" , "Social blunder" , "slip" , "A foolish error" , "Clanger" .)
(Other definitions for error that I've seen before include "Faulty judgment" , "Boob" , "Miscarriage of justice" , "Blunder or mistake" , "Mistake, lapse" .)