Money received in advance? (6)
I believe the answer is:
income
'money received' is the definition.
(I've seen this before)
'in advance?' is the wordplay.
'advance?' becomes 'come' (I've seen this in other clues**).
'in'+'come'='INCOME'
(Other definitions for income that I've seen before include "Earned or unearned revenue." , "Financial gain accruing over a given period of time" , "See 12" , "Money received on which tax is payable" , "Money received for work or from investment" .)