Motorboat put to sea (6)
I believe the answer is:
launch
'motorboat' is the definition.
(launch is a kind of motorboat)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for launch that I've seen before include "Set (a boat) afloat" , "Rocket journey's starting point" , "Of ship, formally set afloat" , "Boat - set in motion" , "Craft - project" .)