Load on vessel includes scraps ultimately given to crow (8)
I believe the answer is:
boastful
'given to crow' is the definition.
(likely to boast or crow)
'load on vessel includes scraps ultimately' is the wordplay.
'load on vessel' becomes 'boatful' (a boat's worth of cargo).
'includes' means one lot of letters goes inside another.
'ultimately' suggests the final letters.
The final letter of 'scraps' is 's'.
'boatful' placed around 's' is 'BOASTFUL'.
(Other definitions for boastful that I've seen before include "Talking with excessive pride in oneself" , "Loudly conceited" , "Talking with excessive pride in one's own ability" , "Given to blowing one's own trumpet" , "Cocky" .)