Retired American cooking his Japanese dish (5)
I believe the answer is:
sushi
'japanese dish' is the definition.
(I've seen this in another clue)
'retired american cooking his' is the wordplay.
'retired' is a reversal indicator.
'american' becomes 'us' (abbreviation for United States).
'cooking' indicates an anagram (cook can mean to falsify or distort).
'us' reversed gives 'su'.
'his' with letters rearranged gives 'shi'.
'su'+'shi'='SUSHI'
(Other definitions for sushi that I've seen before include "Raw fish dishes" , "Cold rice dish, often with raw fish" , "Japanese rice-based dish" , "'Dish of rice, vegetables and raw fish (5)'" , "Japanese rice and raw fish dish" .)