Today, XMPie does not recommend combining credit card payment with approval process.
The reason for this is that the payment is taken when the order is submitted by the customer - IE before the approver has approved it ( and before the approver has possibly edited an item changing the value/cost of the order ).
By default, you cannot put a credit card clearing provider on a store that has approval process defined - or vice versa.
However, you can permit it, but editing the clearing provider plugin pair and specifically permitting the clearing provider to be used on a store with an approval process.
That said, it is still not addressing your question about having the approver actually pay for the order...
Of course, you are welcome to submit a feature request for the product manager to consider and prioritize in his development schedule.
Possibly a manual work around could be to:
* use invoice clearing - which would allow the order to be accepted without credit card payments.
* when the approver approves the order, use the queue mechanism to create a specific order handling queue for these order to go into as a temporary holding queue until payment is received
* the queue can be configured with a trigger to send the approver an email with details on how to pay for the order
* a store administrator would have to manually move the orders to the usual production queues once the payment has been received, or you could
* write custom order handling actions to check for payment and move the order items once payment has cleared.