Longs to make gains after a year (6)
I believe the answer is:
yearns
'longs' is the definition.
('yearn' can be a synonym of 'long')
'gains after a year' is the wordplay.
'gains' becomes 'earns' ('earn' can be a synonym of 'gain').
'after' says to put letters next to each other.
'a year' becomes 'y'.
'earns' after 'y' is 'YEARNS'.
'to make' is the link.
(Other definitions for yearns that I've seen before include "'Craves, longs for (6)'" , "Craves, longs intensely" , "Desires strongly" , "Longs for, pines" , "'Hankers, longs (6)'" .)