Speedboat's trail (4)
I believe the answer is:
wake
'speedboat's trail' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for wake that I've seen before include "pre-funeral event" , "Traditional Irish tribute to corpse before burial, lots of toasts" , "Come to - funereal gathering" , "Rouse" , "Vigil held over a corpse" .)