American aboard vessel refusing soft Japanese food (5)

I believe the answer is:
sushi
'japanese food' is the definition.
(sushi is a type of Japanese food)
'american aboard vessel refusing soft' is the wordplay.
I cannot really see how this works, but
'american' could be 'us' (abbreviation for United States) and 'us' is found within the answer.
'soft' could be 'sh' and 'sh' is found within the answer.
A single letter 'i' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sushi that I've seen before include "Cold rice balls with raw fish" , "Exotic food" , "fare from Japan" , "Fated" , "Oriental food" .)
