Earnings once I’m working (6)
I believe the answer is:
income
'earnings' is the definition.
(thesaurus)
'once i'm working' is the wordplay.
'working' indicates anagramming the letters.
'once'+'im'='onceim'
'onceim' anagrammed gives 'INCOME'.
(Other definitions for income that I've seen before include "Remunerations, takings" , "What do you make" , "Money gained over time" , "See 12" , "Money earned" .)