Upper floor of seats not right for kitchen area (6)
I believe the answer is:
'kitchen area' is the definition.
(galley can mean a ship's kitchen)
'upper floor of seats not right' is the wordplay.
'upper floor of seats' becomes 'gallery' (as in the gallery in a theatre).
'not' suggests deleting specific letters.
'right' becomes 'r' (common abbreviation).
'gallery' with 'r' taken out is 'GALLEY'.
'for' is the link.
(Other definitions for galley that I've seen before include "Trireme" , "Oared ship - ship's kitchen" , "Printer's proof" , "On-board cooking area" , "in which slaves may have a row?" .)