Restaurant has tail of lobster in gravy (6)
I believe the answer is:
bistro
'restaurant' is the definition.
(I know that bistro is a type of restaurant)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for bistro that I've seen before include "Small informal french-style resturaunt" , "Small informal French restaurant" , "Small inexpensive eatery" , "Cheap restaurant" , "'Small, inexpensive restaurant (6)'" .)