South America greeting Japanese dish (5)
I believe the answer is:
sushi
'japanese dish' is the definition.
(type of Japanese food)
'south america greeting' is the wordplay.
'south' becomes 's' (abbreviation).
'america' becomes 'US' (United States).
'greeting' becomes 'hi' (hi is a kind of greeting).
's'+'us'+'hi'='SUSHI'
(Other definitions for sushi that I've seen before include "Asian food" , "Asian dish" , "Food from Japan" , "'Dish of rice, vegetables and raw fish (5)'" , "Rice and raw fish wrapped in seaweed" .)