Restaurant has tail of lobster in gravy (6)

I believe the answer is:

bistro

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'restaurant' is the definition.
(I know that bistro is a type of restaurant)

I can't explain the rest of the clue.

(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)'" .)

I've seen this clue in The Times.

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