Trace viewer regularly introducing Top Gear driver (7)
I believe the answer is:
Here is my best explanation:
'trace' is the definition.
('vestige' can be a synonym of 'trace')
'introducing top gear driver' is the wordplay.
'introducing' means to remove the last letter.
'top' becomes 'vest' (I've seen this before).
'gear driver' becomes 'tige' (I can't explain this - if you can you should believe this answer much more).
'vest' with its last letter removed is 'ves'.
'viewer regularly' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
(Other definitions for vestige that I've seen before include "2 [HINT]", "'Shadow, trace (7)'", "Trace, remnant", "Small trace", "Suggestion", "(Last) trace", "what's left over", "Give set for a surviving trace", "Slight amount, trace" and "Trace or shadow of something that once existed".)