Yank in powerful boat (3)
I believe the answer is:
tug
I believe this clue is a double definition.
'yank' is the first definition.
(both can mean to pull sharply)
'powerful boat' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for tug that I've seen before include "Tow (of war?)" , "Boat to pull larger one" , "Haul" , "Small boat for towing others" , "Pull jerkily" .)