Wow, other ranks will eat free in hall (8)
I believe the answer is:
corridor
'hall' is the definition.
(thesaurus)
'wow other ranks will eat free' is the wordplay.
'wow' becomes 'cor'.
'other ranks' becomes 'or' (military abbreviation).
'will eat' means one lot of letters goes inside another.
'free' becomes 'rid' ('rid' can be a synonym of 'free').
'cor'+'or'='coror'
'coror' placed around 'rid' is 'CORRIDOR'.
'in' acts as a link.
(Other definitions for corridor that I've seen before include "Long passageway" , "Passage connecting rooms" , "Indoor passage" , "Enclosed passageway wtih rooms off" , "Passageway in building" .)