Trimmer vessel (7)
I believe the answer is:
clipper
I believe this is a double definition.
'trimmer' is the first definition.
(device which trims or clips)
'vessel' is the second definition.
(clipper is a kind of vessel)
(Other definitions for clipper that I've seen before include "What provides trim" , "Sailing-ship" , "that has slight collision with another?" , "under sail" , "used to dock" .)