Fatuous paper written by attorney (4)
I believe the answer is:
daft
'fatuous' is the definition.
(thesaurus)
'paper written by attorney' is the wordplay.
'paper' becomes 'ft' (the Financial Times newspaper).
'written by' says to put letters next to each other.
'attorney' becomes 'DA' (District Attorney).
'ft' after 'da' is 'DAFT'.
(Other definitions for daft that I've seen before include "Idiotic" , "Bats!" , "Barmy, crackers" , "Informally crazy as a brush" , "Half-witted" .)