Competitor who's earning very attractive return (6)
I believe the answer is:
profit
'return' is the definition.
(return can mean profit or gain)
'competitor who's earning very attractive' is the wordplay.
I cannot quite see how this works, but
'attractive' could be 'fit' (fit can informally mean attractive) and 'fit' is found in the answer.
The remaining letters 'pro' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for profit that I've seen before include "Gain from employment of capital" , "Use" , "Clean up" , "Surplus earnings" , "Gain, return on investment" .)