Dish of the day: southern fried plaice (7)
I believe the answer is:
special
'dish of the day' is the definition.
(I've seen this before)
'southern fried plaice' is the wordplay.
'southern' becomes 's' (abbreviation).
'fried' indicates an anagram.
'plaice' anagrammed gives 'pecial'.
's'+'pecial'='SPECIAL'
(Other definitions for special that I've seen before include "Exceptional or particular" , "Distinct from and usually better" , "Dish not on usual menu" , "Particular, peculiar" , "Particular, distinctive" .)