Revenue for a company in mine workings (6)
I believe the answer is:
income
'revenue' is the definition.
(both can mean money made)
'company in mine workings' is the wordplay.
'company' becomes 'com' (as in .com).
'in' indicates putting letters inside.
'mine workings' becomes 'ine' (I can't justify this - if you can you should give a lot more credence to this answer).
'com' inserted inside 'ine' is 'INCOME'.
'for a' is the link.
Can you help me to learn more?
(Other definitions for income that I've seen before include "What do you make" , "Money gained from work or investment" , "Returns" , "Money received for work or from investment" , "Salary" .)