Bar in club is trouble (6)
I believe the answer is:
bistro
'bar' is the definition.
(I have seen 'French bar' mean 'bistro' so perhaps 'bar' could also mean 'bistro')
'in club is trouble' is the wordplay.
'in' indicates a hidden word.
'BISTRO' is hidden in the letters of 'club is trouble'.
(Other definitions for bistro that I've seen before include "Intimate eatery" , "Cafe/restaurant" , "Orbits (anag)" , "Small inexpensive eatery" , "Modest restaurant" .)