Unfortunately I peter out going into a spin (9)
I believe the answer is:
pirouette
'a spin' is the definition.
(I know that pirouette is a type of spin)
'unfortunately i peter out' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'i'+'peter'+'out'='ipeterout'
'ipeterout' with letters rearranged gives 'PIROUETTE'.
'going into' is the link.
(Other definitions for pirouette that I've seen before include "Spin on one foot" , "Rapid spin of the body on the toes in ballet" , "Dancer's twirl" , "Balletic whirl" , "A dancer's spinning movement on tiptoe" .)