100 entering to praise returning noble (5)
I believe the answer is:
ducal
'noble' is the definition.
(I've seen this before)
'100 entering to praise returning' is the wordplay.
'100' becomes 'c' (Roman numeral).
'entering' means one lot of letters goes inside another.
'to praise' becomes 'laud' (lauding is a kind of praising).
'returning' is a reversal indicator.
'c' put into 'laud' is 'lacud'.
'lacud' reversed gives 'DUCAL'.
(Other definitions for ducal that I've seen before include "Relating to a duke" , "Relating to a noble" , "Relating to one level of nobility" , "Peer's" , "Like a noble" .)