Charge for professional services (3)
I believe the answer is:
fee
'charge for professional services' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for fee that I've seen before include "Payment to a professional for services" , "Sum payable to professional person for services" , "Sum payable to, say, barrister" , "Amount paid for job" , "Cost" .)