It carries the commander of the fleet (8)
I believe the answer is:
flagship
'it carries the commander of the fleet' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for flagship that I've seen before include "An organisation's most important thing" , "Admiral's craft in a fleet" , "leader of fleet" , "Something of the greatest importance (to an admiral?)" , "Pre-eminent product" .)