Every year, a year's earnings? (3)
I believe the answer is:
pay
'earnings?' is the definition.
('pay' can be a synonym of 'earnings')
'every year a year's' is the wordplay.
'every year' becomes 'pa' (per annum).
'a year' becomes 'y'.
'pa'+'y'='PAY'
(Other definitions for pay that I've seen before include "profitable" , "stop possible leaks on board" , "Remuneration" , "Reward for work" , "Remunerate" .)