Boat docked and king carried in first-rate car (7)
I believe the answer is:
ferrari
'car' is the definition.
'boat docked and king' is the wordplay.
'boat' becomes 'ferry' (ferry is a kind of boat).
'docked' means to remove the last letter (to dock can mean to remove the tail of an animal).
'and' says to put letters next to each other.
'king' becomes 'ari' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ferry' with its final letter taken away is 'ferr'.
'ferr'+'ari'='FERRARI'
'carried in first-rate' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for ferrari that I've seen before include "Sports car brand" , "Type of racing car" , "Italian racing car company" , "Italian sports car" .)