Roomy with a spectacularly audacious exterior (8)
I believe the answer is:
spacious
'roomy' is the definition.
(I know that roomy can be written as spacious)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for spacious that I've seen before include "wide-ranging" , "Big and roomy" , "Having plenty of room" , "Roomy, not congested" , "Roomy or expansive" .)