Russian royal dynasty (7)
I believe the answer is:
romanov
'russian royal dynasty' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for romanov that I've seen before include "Russian imperial line that ruled from 1613 to 1917" , "Russian house" , "one of 23 [DYNASTY]" , "(Member of) Russian imperial dynasty" , "Russian dynasty before the Bolshevik Revolution" .)