Facile nonsense shortly rejected (4)
I believe the answer is:
glib
'facile' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for glib that I've seen before include "freedom of speech?" , "Bush" , "Insincerely fluent" , "Smooth-tongued" , "Of speech, facile but insincere" .)