Film electrician's outright blunder (5)
I believe the answer is:
gaffe
'blunder' is the definition.
(I know that gaffe is a type of blunder)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gaffe that I've seen before include "embarrassing error" , "Boob" , "Something wrong" , "indiscreet remark" , "slip" .)