Money earned with time (4)
I believe the answer is:
wage
'money earned' is the definition.
(I've seen this before)
'with time' is the wordplay.
'with' becomes 'w' (abbreviation).
'time' becomes 'age' (age is a kind of time**).
'w'+'age'='WAGE'
(Other definitions for wage that I've seen before include "Regular money for work" , "Regular amount of income" , "Carry on - remuneration" , "Regular payment for work" , "Money paid to worker" .)