Boat that's easier to carry (7)
I believe the answer is:
lighter
This clue is a double definition.
'boat' is the first definition.
(lighter is a kind of boat)
'easier to carry' is the second definition.
'that's' is the link.
(Other definitions for lighter that I've seen before include "Barge (more likely to float?)" , "craft" , "Smoking accessory" , "Vessel" , "- boot; - bun; - ware" .)