Restaurant taken over by pub is troubled (6)
I believe the answer is:
bistro
'restaurant' is the definition.
(I know that bistro is a type of restaurant)
'taken over by pub is troubled' is the wordplay.
'taken over by' indicates the answer is hidden within the clue.
'BISTRO' is hidden within 'pub is troubled'.
(Other definitions for bistro that I've seen before include "Eating place" , "family concern perhaps" , "somewhere to eat" , "Little restaurant" , "A small informal restaurant from France" .)