Magnificent leading couples from Paris, lavish times always! (8)
I believe the answer is:
palatial
'magnificent' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
(Other definitions for palatial that I've seen before include "Stately, imposing" , "Grandiose" , "Majestic -- spacious" , "Huge, luxurious (rooms)" , "Big, luxurious (accommodation)" .)