It would be extremely helpful to have the ability to "inquire" or "Request Info" in the approval process in the event that an approver would like more clarity from a requestor.
Along with "Approve" and "Reject", perhaps a button or link saying "Request Info". Upon clicking, something allows the approver to input their inquiry and this information is sent to the requestor via email.
Once the requestor responds, the approval is resent with the original information along with the info requested and response.
Essentially, some functionality that allows the approver to question the requestor before making a decision.