Thanks college for income (7)
I believe the answer is:
takings
'income' is the definition.
(I've seen this before)
'thanks college' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'college' becomes 'kings'.
'ta'+'kings'='TAKINGS'
'for' acts as a link.
(Other definitions for takings that I've seen before include "What's in the till" , "Monetary receipts" , "Cash receipts" , "Income from sales, etc" , "Income from transactions" .)