What is the ruling on taking a deposit for the purchase of a commodity that is not with the seller and is manufactured specifically for the buyer?

Since the questioner is the seller of clothes and not the manufacturer, the transaction can be structured as a parallel manufacturing contract (Istisna al-Muwazi), which does not require the full price to be paid at the contract session for its validity. Rather, the price may be paid in advance, or its entirety or a portion of it may be deferred.