Posh hotel (4)
I believe the answer is:
ritz
'posh hotel' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ritz that I've seen before include "(Expensive) London hotel" , "Puttin' on the -- (song)" , "Elegant hotel" , "Swiss hotelier, who founded an international chain, d. 1918" , "Swiss hotelier, creator of a chain of elegant hotels, d. 1918" .)