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 before)
'a nasty snag at the hotel' is the wordplay.
'a nasty' is an anagram indicator.
'at' says to put letters next to each other.
'the hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'snag' with letters rearranged gives 'gnas'.
'gnas'+'h'='GNASH'
'when there's' acts as a 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" .)