Pay in advance (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
income
'pay' is the definition.
(thesaurus)
'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." , "Remunerations, takings" , "Money received for work or from investment" , "Financial gain accruing over a given period of time" , "Returns" .)