Tiller of vessel touring miles behind lake (9)
I believe the answer is:
ploughman
'tiller' is the definition.
(someone who tills on a farm)
'vessel touring miles behind lake' is the wordplay.
I cannot really understand how this works, but
'miles' could be 'm' (common abbreviation) and 'm' is found in the answer.
'lake' could be 'lough' (lough is a kind of lake) and 'lough' is located in the answer.
'vessel' could be 'pan' (vessel or container for cooking) and 'pan' is found in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
(Other definitions for ploughman that I've seen before include "One with shares in Labour" , "Tiller of soil" , "Adult having a share" , "Agricultural worker (having lunch?)" , "His groundbreaking work" .)