Dignified let-up in support
I believe the answer is:
stately
'dignified' is the definition.
(similar in meaning)
'let-up in support' is the wordplay.
'up' indicates anagramming the letters (letters get chucked up).
'in' is an insertion indicator.
'support' becomes 'stay' (stay is a kind of support).
'let' with letters rearranged gives 'tel'.
'tel' going within 'stay' is 'STATELY'.
(Other definitions for stately that I've seen before include "Grand, dignified" , "Courtly; imposing" , "August" , "Impressive in appearance; majestic" , "Imperial" .)