Illustrious person of wealth, extremely likeable (5)
I believe the answer is:
noble
'illustrious' is the definition.
(I've seen this before)
'person of wealth extremely likeable' is the wordplay.
'person of wealth' becomes 'nob' (informal term for an upper-class or rich person).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'likeable' with its middle taken out is 'le'.
'nob'+'le'='NOBLE'
(Other definitions for noble that I've seen before include "Lord" , "Having high moral character" , "titled person" , "with a title?" , "Dignified" .)