Idle army deployed in visionary fashion? (8)
I believe the answer is:
dreamily
'in visionary fashion?' is the definition.
(in a dreamy way)
'idle army deployed' is the wordplay.
'deployed' indicates an anagram.
'idle'+'army'='idlearmy'
'idlearmy' is an anagram of 'DREAMILY'.
(Other definitions for dreamily that I've seen before include "As if in a reverie" , "Vaguely" , "in abstracted way" .)