Lynn —, Canadian dancer who created the lead role in 1967 Kenneth MacMillan one-act ballet Anastasia (7)
I believe the answer is:
seymour
(Other definitions for seymour that I've seen before include "Jane -, mother of Edward VI" , "Royally, Jane" , "15 [JANE], one of the wives" , "Jane --, queen" , "Henry VIII's wife Jane" .)