Grind the teeth when there's a nasty snag at the hotel (5)
I believe the answer is:
gnash
'grind the teeth' is the definition.
(I've seen this in another clue)
'a nasty snag at the hotel' is the wordplay.
'a nasty' indicates anagramming the letters (a nasty or wrong spelling).
'at' is a charade indicator (letters next to each other).
'the hotel' becomes 'h' (phonetic alphabet).
'snag' is an anagram of 'gnas'.
'gnas'+'h'='GNASH'
'when there's' is the link.
(Other definitions for gnash that I've seen before include "grate" , "Strike one's teeth together in rage" , "Hangs (anag.)" , "Grind one's teeth" , "grinding action" .)