Cafe allows writer to hold empty seat (6)
I believe the answer is:
bistro
'cafe' is the definition.
(I've seen this in another clue)
'writer to hold empty seat' is the wordplay.
'writer' becomes 'biro' (type of pen, something which writes).
'to hold' is an insertion indicator.
'empty' says to hollow out the word (remove centre letters).
'seat' with its centre taken out is 'st'.
'biro' placed around 'st' is 'BISTRO'.
'allows' is the link.
(Other definitions for bistro that I've seen before include "Small informal French cafi" , "Cafe/restaurant" , "Orbits (anag)" , "Modest restaurant" , "Little restaurant" .)