Go off topic (7)
I believe the answer is:
digress
'go off topic' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for digress that I've seen before include "Wander from a topic" , "Leave the point" , "Turn aside (from the main subject?)" , "Wander from one's path" , "Wander from subject" .)