As a fib, it's among the silliest (3)
I believe the answer is:
lie
'as a fib' is the definition.
I can't tell whether this definition defines the answer.
'among the silliest' is the wordplay.
'among' says the answer is hidden in the clue.
'LIE' can be found hidden inside 'silliest'.
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "habitat for animal or bird" , "Commit perjury" , "Stay hidden" , "Porky" , "Assume a horizontal position" .)