Popular firm and writer making profit (6)
I believe the answer is:
income
'profit' is the definition.
(thesaurus)
'popular firm and writer' is the wordplay.
'popular' becomes 'in'.
'firm' becomes 'co' (a firm is a company).
'and' says to put letters next to each other.
'writer' becomes 'me' (the person who is writing these clues).
'in'+'co'+'me'='INCOME'
'making' acts as a link.
(Other definitions for income that I've seen before include "Money coming in" , "What do you make" , "Remunerations, takings" , "Earned or unearned revenue." , "Coin me! (anag)" .)