Equipment for tennis professional with suitable final income (3,6)
I believe the answer is:
net profit
'income' is the definition.
(I know that net profit is a type of income)
'equipment for tennis professional with suitable final' is the wordplay.
'equipment for tennis' becomes 'net' (tennis net).
'professional' becomes 'pro' (abbreviation).
'with' says to put letters next to each other.
'suitable' becomes 'fit' (similar in meaning).
'final' is a charade indicator (letters next to each other).
'net'+'pro'+'fit'='NET PROFIT'
(Other definitions for net profit that I've seen before include "What's finally made" , "Actual money to be made" , "Earnings after all deductions" , "return from business" , "Excess of sales over costs for potent fir" .)