Advance fee (8)
I believe the answer is:
retainer
'advance fee' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for retainer that I've seen before include "Fee could be the answer" , "Old servant - fee paid in advance" , "Long-serving member of staff" , "Family servant; barrister's fee" , "Down-payment for Eritrean" .)