Futile as miles off (7)
I believe the answer is:
aimless
'futile' is the definition.
(I've seen this in another clue)
'as miles off' is the wordplay.
'off' indicates an anagram.
'as'+'miles'='asmiles'
'asmiles' is an anagram of 'AIMLESS'.
(Other definitions for aimless that I've seen before include "Without purpose or plan" , "lacking direction" , "not knowing where to go?" , "Without objectives" , "Like characters in 5D {WAITING FOR GODOT]" .)