Obscure allegations referring to fees required of customers (5,7)

'of customers' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.

'obscure allegations referring to fees' is the wordplay.
I cannot really see how this works, but
'obscure' could be 'cover' (obscure can mean to cover or eclipse) and 'cover' is found within the answer.
'fees' could be 'charges' (I've seen this in another clue) and 'charges' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

'required' is the link.

Can you help me to learn more?