A second attempt to bring in one off-course (6)
I believe the answer is:
astray
'off-course' is the definition.
(I've seen this before)
'a second attempt to bring in one' is the wordplay.
'a second' becomes 'as' (I've seen this in other clues**).
'attempt' becomes 'try' (I've seen this before).
'to bring in' is an insertion indicator.
'one' becomes 'a'.
'try' placed around 'a' is 'tray'.
'as'+'tray'='ASTRAY'
(Other definitions for astray that I've seen before include "in the wrong place" , "wrong way" , "Going wrong" , "Wandering off the track" , "(Gone) in wrong direction" .)