Notice dispute off course (6)
I believe the answer is:
adrift
'off course' is the definition.
(adrift can mean off course or astray)
'notice dispute' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'dispute' becomes 'rift' (rift can mean a feud or dispute).
'ad'+'rift'='ADRIFT'
(Other definitions for adrift that I've seen before include "without purpose or direction" , "Floating unattached as at sea" , "Undirected" , "Moving aimlessly, unfastened" , "(Of ship) out of control" .)