Small bar or informal restaurant (6)
I believe the answer is:
bistro
I believe this is a double definition.
'small bar' is the first definition.
(I've seen this in another clue)
'informal restaurant' is the second definition.
(I've seen this before)
(Other definitions for bistro that I've seen before include "somewhere to eat" , "Eating place" , "Cheap restaurant" , "Cafe bar" , "Small bar-cum-restaurant" .)