A charge that will make you feel robbed of pounds! (3)
I believe the answer is:
fee
'a charge' is the definition.
(I know that fee is a type of fixed charge)
'feel robbed of pounds' is the wordplay.
'robbed of' indicates named letters should be taken away.
'pounds' becomes 'l' (L can represent the monetary pound).
'feel' with 'l' removed is 'FEE'.
'that will make you' is the link.
(Other definitions for fee that I've seen before include "price" , "(Entry) charge" , "Charge for professional services" , "Payment to a professional for services" , "Amount paid for job" .)