Imperial, majestic (5)
I believe the answer is:
regal
I believe this clue is a double definition.
'imperial' is the first definition.
(synonyms)
'majestic' is the second definition.
(synonyms)
(Other definitions for regal that I've seen before include "King's" , "Grand and imposing" , "Magnificent, dignified" , "Imperial, majestic" , "befitting a king" .)