Falsehood is not to be stood for (3)
I believe the answer is:
lie
'falsehood' is the definition.
(I know that lie is a type of falsehood)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "Piece of fiction" , "Be prostrate" , "found" , "habitat for animal or bird" , "Tell tales" .)