Off course (6)
(Other definitions for adrift that I've seen before include "Unanchored - lost" , "Afloat without control" , "(Of ship) out of control" , "without guidance?" , "not settled" .)
'off course' is the definition.
(to be led astray is to be led off course)
This is all the clue.
(Other definitions for astray that I've seen before include "Wandering off the track" , "Wandering off the path" , "Gone off the right path" , "on the wrong road" , "in the wrong place" .)