Initially served up some hotpot, Irish dish (5)
I believe the answer is:
sushi
'dish' is the definition.
(sushi is a kind of dish)
'initially served up some hotpot irish' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'served up some hotpot irish' is 'SUSHI'.
(Other definitions for sushi that I've seen before include "Oriental food" , "rice dishes" , "Asian food" , "Rice and raw fish wrapped in seaweed" , "'Dish of rice, vegetables and raw fish (5)'" .)