Plot to acquire boat paid off (6)
I believe the answer is:
bribed
'paid off' is the definition.
(I've seen this in another clue)
'plot to acquire boat' is the wordplay.
'plot' becomes 'bed' (a plot of land).
'to acquire' indicates putting letters inside.
'boat' becomes 'rib' (I can't explain this - if you can you should believe this answer much more).
'bed' enclosing 'rib' is 'BRIBED'.
Can you help me to learn more?
(Other definitions for bribed that I've seen before include "Gave money to suborn" , "Corrupted with money" , "Given a sweetener" , "Made illegal payments in exchange for favours" .)