Eatery with its own lingo (5)
I believe the answer is:
diner
'eatery with its own lingo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for diner that I've seen before include "Buffet car" , "One taking a meal" , "Railway carriage serving meals" , "Restaurant customer" , "One eating a meal" .)