New army leak is nonsense (8)
I believe the answer is:
malarkey
'is nonsense' is the definition.
(I've seen this before)
'new army leak' is the wordplay.
'new' is an anagram indicator.
'army'+'leak'='armyleak'
'armyleak' anagrammed gives 'MALARKEY'.
(Other definitions for malarkey that I've seen before include "Cock" , "Slangy humbug or nonsense - sounds like Irish name" , "Nonsensical stuff" , "Absurd talk" , "Idle words" .)