A pound a point? Don't you believe it! (3)
I believe the answer is:
lie
'a pound' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'a point? don't you believe it' is the wordplay.
'LIE' is hidden in amongst the letters.
However, I'm unsure how this is indicated.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "Prevarication" , "Tell tales" , "habitat for animal or bird" , "Disinformation" , "Equivocate" .)