Payment not initially for one man-hour worked (10)
I believe the answer is:
Here is my best explanation:
'payment' is the definition.
(honorarium is a kind of payment)
'not initially for one man-hour worked' is the subsidiary indication.
'not initially' means to remove the first letter.
'one' becomes 'i' (roman numeral).
'worked' indicates anagramming the letters.
'forimanhour' with its first letter taken away is 'orimanhour'.
'orimanhour' anagrammed gives 'honorarium'.
(Another definition for honorarium that I've seen is "Nominal payment for professional services".)