Prepared us his Japanese dish (5)
I believe the answer is:
sushi
'japanese dish' is the definition.
(I've seen this before)
'prepared us his' is the wordplay.
'prepared' indicates anagramming the letters.
'us'+'his'='ushis'
'ushis' with letters rearranged gives 'SUSHI'.
(Other definitions for sushi that I've seen before include "fare from Japan" , "put away in Japan" , "oriental dish" , "Rice, seafood cuisine" , "Japanese vinegared rice dish" .)