To settle, one needs income increased (3,2)
I believe the answer is:
pay up
'to settle' is the definition.
(I know this)
'income increased' is the wordplay.
'income' becomes 'pay' (income from a job).
'increased' becomes 'up' (something that's up has increased or risen).
'pay'+'up'='PAY UP'
'one needs' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for pay up that I've seen before include "Give me the money!" , "Settle" , "Discharge a debt" , "Hand over the money" .)