Dish available in Mississippi eatery (3)
I believe the answer is:
pie
'dish' is the definition.
(I've seen this before)
'available in mississippi eatery' is the wordplay.
'available in' indicates the answer is hidden within the clue.
'PIE' can be found hidden inside 'mississippi eatery'.
(Other definitions for pie that I've seen before include "In the sky, this dish is impractical" , "something with custard, say" , "Bird; pastry" , "See 6" , "Pasty - former Indian coin - mixed type - bird" .)