Bill carrying nothing aboard capsized vessel (4)
I believe the answer is:
boat
'vessel' is the definition.
(I know that vessel can be written as boat)
'bill carrying nothing aboard capsized' is the wordplay.
'bill' becomes 'tab' (tab is a kind of bill).
'carrying nothing' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'aboard' means one lot of letters goes inside another.
'capsized' shows that the letters should be reversed in order.
'tab' enclosing 'o' is 'taob'.
'taob' backwards is 'BOAT'.
(Other definitions for boat that I've seen before include "See 1" , "Water craft" , "See 18" , "See 12 Down" , "cat, for example" .)