Dance that's unexpected (5)
I believe the answer is:
twist
I believe this clue is a double definition.
'dance' is the first definition.
(twisting is a kind of dancing)
'that's unexpected' is the second definition.
(as in a plot twist)
(Other definitions for twist that I've seen before include "surprising plot development" , "Twirl" , "Convolute" , "See Oliver" , "Intertwine, contort" .)