A fellow eloquent and rich (8)
I believe the answer is:
affluent
'rich' is the definition.
(similar in meaning)
'a fellow eloquent' is the wordplay.
'fellow' becomes 'F' (abbreviation - of a society etc.).
'eloquent' becomes 'fluent' (synonyms).
'a'+'f'+'fluent'='AFFLUENT'
'and' acts as a link.
(Other definitions for affluent that I've seen before include "Well-heeled" , "Well-off" , "Loaded" , "Wealthy, rich" , "Very well off, quite rich" .)