There is a special order of 100 T-Shirts at a price of $20. A 50% deposit was put down and the rest will be paid when the T-Shirts arrive.

Debit Cash for the amount received
Debit Accounts Receivable for the difference
Credit Unearned Revenue for the total price.

If I read the question correctly, the trader has placed an order for T Shirts and has made an advance payment. The T shirts have not yet been delivered. This would be an advance to supplier.

Debit Supplier $1000
Credit Cash $1000

If the company ordered the shirts, then the entry would be:
Debit appropriate account like an expense account (if giving to employees or to customers), Merchandise Inventory (if selling the shirt), or Purchases for the total amount
Credit Cash for the amount paid
Credit Accounts Payable for the amount to be paid at a later time

Pready, your entry for purchases is correct if and only if the T Shirts have been received. According to the question, the merchandise has not arrived yet.