Payment, say about half a dollar (6)
I believe the answer is:
salary
'payment' is the definition.
(salary is a kind of payment)
'say about half a dollar' is the wordplay.
'about' means one lot of letters goes inside another.
'half a' means to take half the letters.
'dollar' cut in half is 'lar'.
'say' going around 'lar' is 'SALARY'.
(Other definitions for salary that I've seen before include "Monthly pay" , "Regular earnings" , "payment only for non-manual workers" , "Remuneration for Ray and Sal" , "Wages" .)