Diner where writer holds empty seat (6)
I believe the answer is:
bistro
'diner' is the definition.
(thesaurus)
'writer holds empty seat' is the wordplay.
'writer' becomes 'biro' (I've seen this before).
'holds' indicates putting letters inside.
'empty' says to hollow out the word (remove centre letters).
'seat' with its middle taken out is 'st'.
'biro' enclosing 'st' is 'BISTRO'.
'where' is the link.
(Other definitions for bistro that I've seen before include "Small restaurant - robs it (anag)" , "Orbits (anag)" , "Coming out of restaurant" , "Small French bar and restaurant" , "Little restaurant" .)