Rob worked around first restaurant (6)
I believe the answer is:
Here is my best explanation:
'restaurant' is the definition.
(bistro is a kind of restaurant)
'rob worked around first' is the wordplay.
'worked' indicates an anagram.
'around' means one lot of letters goes inside another.
'first' becomes 'ist' (**).
'rob' anagrammed gives 'bro'.
'bro' going around 'ist' is 'BISTRO'.
(Other definitions for bistro that I've seen before include "Informal French restaurant", "Small informal French restaurant", "Coming out of restaurant", "Inexpensive restaurant", "Eating place", "Cafe bar", "Small informal french-style resturaunt", "somewhere to eat", "Cheap restaurant" and "Eatery".)