Russian dynasty (7)
I believe the answer is:
romanov
'russian dynasty' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for romanov that I've seen before include "Russian emperor" , "Family name of tsars" , "(Member of) Russian imperial dynasty" , "Member of the Russian royal family, 1613 to 1917" , "Russian royal dynasty" .)