Family servant fee paid in advance (8)
I believe the answer is:
retainer
I believe this clue is a double definition.
'family servant' is the first definition.
(I've seen this before)
'fee paid in advance' is the second definition.
(I've seen this before)
(Other definitions for retainer that I've seen before include "Advance fee to reserve someone's services" , "Old servant - fee paid in advance" , "given payment in advance" , "Fee paid to book professional services" , "Holding fee or faithful old servant" .)