Loan debt to be taken from maintenance amount

No, it is not possible for attaching the maintenance order to repay her personal loan, she is just threatening you without any base.

CrPC provides specific procedure for enforcement of maintenance granted under Section 125.

Maintenance arrears and personal loans are two different subjects where separate laws apply. Legally wife (Decree Holder) will be at liberty to file execution for arrears of the awarded amount, which cannot be clubbed with a loan for her maintenance. You have already engaged an able, competent and intelligent lawyer who is well aware about facts and circumstances of the case, what is his / her opinion and advise, have faith and proceed. if it is a real (not hypothetical) problem. Prima facie it is moot court topic for debate or time pass post.