False statement one seen in Facebook? (3)
I believe the answer is:
fib
'false statement' is the definition.
(fib is a kind of false statement)
'one seen in facebook?' is the wordplay.
'one' becomes 'I' (Roman numeral).
'seen in' means one lot of letters goes inside another.
'facebook?' becomes 'fb' (I am not sure about this - if you are sure you should believe this answer much more).
'i' inserted within 'fb' is 'FIB'.
Can you help me to learn more?
(Other definitions for fib that I've seen before include "Little white lie" , "One must be 20 [UNTRUE]" , "Small lie" , "Trivial lie" , "minor piece of fiction" .)