Before hotel used to be clean (4)
I believe the answer is:
wash
'clean' is the definition.
(washing is a kind of cleaning)
'before hotel used to be' is the wordplay.
'before' is a charade indicator (letters next to each other).
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'used to be' becomes 'was' (I've seen this before).
'h' put after 'was' is 'WASH'.
(Other definitions for wash that I've seen before include "Of animals, cleanse by licking" , "Be credible" , "Flow over" , "Stand up" , "The ----, inlet of the North Sea" .)