I dance endlessly around as fantastic terpsichorean (7,6)
I believe the answer is:
isadora duncan
'terpsichorean' is the definition.
(I know that Isadora Duncan is a terpsichorean)
'i dance endlessly around as fantastic' is the wordplay.
'endlessly' means to remove the last letter.
'fantastic' indicates anagramming the letters (a fantastic or improbable ordering of the letters).
'dance' with its final letter taken off is 'danc'.
'danc'+'around'+'as'='dancaroundas'
'dancaroundas' with letters rearranged gives 'sadoraduncan'.
'i'+'sadoraduncan'='ISADORA DUNCAN'
(Other definitions for isadora duncan that I've seen before include "American "inventor" of Modern Dance, 1877-1927" , "dancer" .)