Retire an eccentric old family servant (8)
I believe the answer is:
retainer
'old family servant' is the definition.
(I've seen this before)
'retire an eccentric' is the wordplay.
'eccentric' indicates an anagram.
'retire'+'an'='retirean'
'retirean' anagrammed gives 'RETAINER'.
(Other definitions for retainer that I've seen before include "reduced rent" , "Holding fee or faithful old servant" , "Old servant - fee paid in advance" , "Fee; long-term servant" , "Fee paid to book professional services" .)