Imposing, grand (7)
I believe the answer is:
stately
This clue is a double definition.
'imposing' is the first definition.
(synonyms)
'grand' is the second definition.
(I've seen this in another clue)
(Other definitions for stately that I've seen before include "Grand, dignified" , "Impressive in manner" , "` `In Xanadu did Kubla Khan / A ....... pleasure-dome decree' ' (Coleridge)" , "Imposing, grand" , "Formal; type of home" .)