A halfwit lifted hotel sponge (6)
I believe the answer is:
loofah
'sponge' is the definition.
(loofah is a type of sponge)
'a halfwit lifted hotel' is the wordplay.
'halfwit' becomes 'fool' (halfwit can mean a foolish person).
'lifted' shows that the letters should be reversed in order (going up in down clue).
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'a'+'fool'='afool'
'afool' back-to-front is 'loofa'.
'loofa'+'h'='LOOFAH'
(Other definitions for loofah that I've seen before include "cleaner" , "Vegetable bath sponge" , "Dried part of plant used as a bath sponge" , "Part of fruit used as bath sponge" , "Bath-time scrubber" .)