Errant (4,2,3,4)
I think it could be either:
wide of the mark
(Other definitions for wide of the mark that I've seen before include "Inaccurate" , "Far from true" , "Well off target" .)
'errant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for astray that I've seen before include "Wandering off the track" , "Off the correct track" , "Missing, lost" , "Well off course" , "on the wrong road" .)